Well, I guessed Utimecia might be in Rinoa's body the moment I heard she passed out around the same time as Edea being exorcised. But I didn't think she was specifically laying in wait for this, because that's insane.
Don't forget that Artemisia is from the future - she would have a general idea that a Lunar Cry would have happened around this time, and it's not unreasonable to assume that she somehow knew the Lunatic Pandora could be used to direct the Lunar Cry. She might not have known she'd be brought directly to the Lunar Base, but she wouldn't have needed to; just triggering the Lunar Cry so that Adel's body is dragged down to earth where she can make use of it is all that she really needed. It does require her to know Esthar had stashed Adel's body there, or course, but again, she's from the future, so there's plenty of ways she might have come across that information.
I think that "caused a cataclysmic event just so she could drag Adel's body back to earth where she can make use of it" does wonders to communicate the scale at which Artemisia's planning operates.
Also, now that we've had the full explanation of Ellone's power, I want to mention that I think those limitations are the reason why the orphanage twist was stretched into forcing Zell, Selphie and Quistis into it - because it justifies why Ellone was able to send them into the past: she knew them very well from her orphanage days. And it was narratively important for them to be sent back, because otherwise, if Squall was the only one sent back (with us only learning the other two people being sent back were Irvine and Seifer much later), then Squall could have been able to dismiss the Laguna segments of the story as weird dreams he was having, instead of something that was really happening.
So... that's my best guess for why the orphanage twist was structured in the way it was. I don't know if that could have been handled in a different way that didn't drag Zell and Selphie into it; Quistis is a corner case, in that tying her to the orphanage twists does provides some more depth to her character, but it's clear Zell and Selphie would have benefited from not being part of it, and the only real reason I can see for it is to preserve the integrity of the (more important) Ellone's plotline. Since, if Ellone could just send whoever in the past without meeting them, then this whole section of the plot with dragging Rinoa to the moon wouldn't have been necessary, and obviously the developers really wanted the Lunar Cry sequence to take place. And I don't know I can fault them for that, I just wish they'd found a better way to make it happen than overloading the orphanage twist.
Well, setting that aside, in more translation notes:
Nearly the entirety of the White SeeD ship section, including the incidental dialogue, is nearly word for word the same between the Italian and English version.
There are a few occasional differences, but they're clearly errors from the Italian translators - Edea says that the White SeeD are "curious" rather "cautious" before proceeding to tell us that they're constantly on the move to avoid capture, the White SeeD's leader answer to Squall's comment that "we even have the same salute" is translated to "Edea told us everything stayed the same as when the Garden was founded" instead of the much more logical English translation of "yes, the salute remained the same since Garden was founded", but really there's nothing here that suggests this were more than errors, nor anything that prompts interesting discussion.
The biggest difference is that the White SeeD said that, when they stumbled on the Galbadian fleet in Centra waters, the Italian translation has him say "they were clearly looking for something", whereas the English translation has him say "they were clearly looking for us", which might just be another mistake, but the two words are different enough that I could conceivably see it as a different interpretation, where the Galbadian were looking for something else and the White SeeD stumbled on them due to simple bad luck.
Other than that, the rest of the dialogue is really all the same.
Although it's worth pointing out that, before heading for FH to bring Rinoa to Esthar, it's possible to go back to the White SeeD ship (once you go to Esthar, it disappear from the map and never shows up again, adding to the long, long list of easily missed stuff; this isn't that great a loss, as most of it is incidental dialogue - the only really juicy piece of info that one can collect there is that "the Galbadian recently dredged up some ancient monolith from the bottom of the Sea". This obviously was foreshadowing them showing up later with the Lunatic Pandora in tow, and indicates to us that, while Squall was busy thinking about Rinoa, the enemy was moving in the background, taking advantage of our heroes' lack of attention to their actions. The same information could also have been obtained by talking with people in Deling City before heading to FH, too. It just took, as usual, ignoring the obvious thrust of the plot to check the incidental dialogue of everybody accessible to the player.
Anyway, going back to the walk on the big bridge (where is Gilgamesh when you need him to break through deep character introspection with his strength of personality?), with accompanying Squall monologue, once again there's nothing very different to note about the translation; the speech is identical, which is probably a good thing, keeping the characterization consistent. Does makes this whole translation comparison exercise a bit pointless though, at least for this section.
The salt lake also doesn't feature any changes in dialogue, so nothing to report there.
Which gives the first meaningful change in dialogue during the Laguna dream; the English version has the human laborer tell to Laguna "they give the Mumba half the food and sleep as us humans", but the Italian version says instead "Mumba are more resilient and need only half as much food and sleep as a human", which is a very different take on things. In the English version, the implication is that the Mumba is treated worse than humans, while in the Italian version we're told that's not the case (all the prisoners are mistreated as much as they can handle), which moves the focus on Laguna's helpfulness a bit. It's a minor thing, but with how little changes in translation there have been in Disk 3 (aside from the big one at the very beginning), it seems worth commenting upon. That's all that is different in the Laguna dream, in any case.
One thing I want to note here is that the Weapon Monthly n.1 has the only weapon which, aside from the Gunblades adding finishers to Squall's Renzokuken, isn't just simply made irrelevant by Junctions: just as the text suggests, Selphie's Strange Vision grants 255% HIT upon equipping it, and unlike all of the other stats except LUCK, no item can be used to teach a GF how to Junction HIT - and there's only three GFs who get the ability by default, not to mention the only spell that really matters for HIT is Triple, which you likely want to junction on something else.
While minor, this comes in handy when optimizing a team for fighting opponents which are especially good at avoiding attacks, makes Selphie's the only ultimate weapon aside from Lionheart that is actually meaningful (and note, you can first forge the Strange Vision at the same time you can first forge the Lionheart, ie after obtaining Minitaur's card for the Adamantium) and also adds one extra reason (along with her "can kill even bosses in one hit" Limit) for why Selphie is the best character in combat as well as out of it. Just saying.
Once we get into Esthar, there's some differences in how the discussion with Odine goes. First of all, when he enters after Edea has expressed her desire to be free of Artemisia's control, he doesn't say "I'll just exorcise the Sorceress", instead saying "I'll isolate and contain the Sorceress' magic", which is a more precise explanation and suggest that Edea's Sorceress powers are tied into how Artemisia took control of her. Although how Odine would know this is unclear, it can be handwaved considering he worked for Sorceress Adel and thus likely had chance to study
her power.
Then, rather then "I'll leave this in your hands then", which suggests Edea is putting hope in Odine's reputation, the Italian translation has her say "I trust you, Doctor", which seems more personal; Odine is the one who developed the Junction system the Garden use, so I always took this to suggest that perhaps Edea had been to Esthar before, or else somehow worked with Odine before she founded the Gardens - that there was a personal connection of some sort here. I wonder if the japanese translation would support that sort of reading.
Notably, Squall is actually more threatening in Italin then in English when he addresses Odine, which is interesting considering how the Italian translation so far has been subtly softening him before this point. Instead of the English "We need to see Ellone now!", which comes across a bit unhinged, he says "You aren't allowed to refuse; I'm ready to do anything so we can meet", and with the line being delivered as he slowly walks closer to Odine, it comes across a lot more menacing. Also, the conversation then flows better into Odine's follow up, which is "so, you will use force to make me comply then?", rather than the somewhat non-sequitur "you gonna take me hostage?" he uses in English, before the conversation flows back into Squall's "I don't care".
As far as the incidental dialogue with the NPCs inside of Esthar goes, there's no really substantial changes in the translation, although I did want to point out that, at the shopping mall, it is possible to go from the first shop to the last shop by pressing "left" or "up" on the controller, which spares some times when repeatedly trying to enter it until it hands over the Rosetta Stone. Of note: there are only three Rosetta Stones in the game, one of which is this, one of which was in the D-District Prison as one prize (with a 1 in 255 chance) that could be won from one of the card players you needed to pay to play (I forget which of them), and the third one is in the final dungeon.
Also,
@Omicron, while the difference might seem small right now, as several of the more unique items are gated behind obtaining Tonberri's Familiar ability, both the Esthar Pet Shop and Johnny's Shop (the one you needed to enter multiple times to unlock) have actually a very different choice of items from the standard shops; you might want to visit them again once you have Familiar (and probably after you learned the ability which is unlocked for Tonberri after learning Familiar, which also facilitates easy shopping), as they are quite handy - one for providing Tool Refine materials, and the other for GF customization. Probably the two best shops in the game overall, although all of the Esthar Shops are unique - Cloud's Shop will sell several ammo types that can't otherwise be found (except by refining), once you have Familiar to activate the extra items for it, and a couple of those are more practical to buy (since you have infinite money) than to refine (since the items can be a pain to collect).
Amusingly, once reached the Lunar Gate - after murdering an endless parade of Mesmerize and one Marlboro with Odin's help - the Italian translation is even less willing to tell us where we're going; in the English version, Squall has a line that says "space? Let's think about it...", but the Italian version only has "let me think this over", with no mention of space. It really feels like the game doesn't want to be explicit with things, even if the visuals of what's going to happen are pretty straightforwards.
Nothing of real relevance is changed in the section where Zell has command of the group; I didn't check all of the incidental dialogue in Esthar, so I could have missed something, but the primary plot events kept the same wording. Similarly, nothing on the Lunaside base is changed in any way that seems deserving of commentary. Still, hopefully this information was interesting to somebody!