An interesting thought that occurs to me:
-Prudence
Highest degree of caution of course, to destroy the research and wipe everything of it other than MAYBE if one day Mathilde goes Dark she goes nuts with it.
-Faith
Its a show of piety, certainly, and a powerful one.
But one addendum to this - it robs Ranald of plausible deniability.
If we straight up sacrifice the research and how it is done to him, he knows, and should the other gods get mad at some future outcome, he cannot say "oh you know sometimes your worshippers just do these things". He would know and has to weigh the risks of having to take the consequences if anything goes wrong or the other gods get upset.
And while he's the Gambler, he's not only the Gambler. The Night Prowler can't shroud someone who unmasked themselves.
I expect a "continue, you have my interest" result to be only likely on a 1/6 roll, whether or not he personally was offended.
-Truth
Here we need to be careful.
I'm concerned but not overly worried about Ranald getting mad about it at our current juncture.
We're one of his favorite amusements, he checks in very often, and we literally carry a beacon of his power on our person. If we explore this, he can eventually find out, and it is unlikely that we'd know even if he did, because if he cannot conceal himself, he wouldn't be much of a Night Prowler.
So to take a look at his aspects to try to divine the reaction:
-Gambler - Largely neutral, reveling in the ENORMOUS gamble, but ready to enforce the consequences.
-Night Prowler - This IS a novel form of theft. Approving...provided it does not come to light. Also likely flips to disapproving if it seeks to end the mystery of Ranald.
-Deceiver - Falsifying a god's signature? Approving, once again, provided it doesn't get exposed. Also likely flips to disapproving if it seeks to end the mystery of Ranald.
-Protector - Should the other gods find out, then likely disapproving, for their retaliations are likely to hurt quite a lot of people.
So from here, what paths of Truth dare we walk?
-Studying Ranald's energy further, I think, is a non-starter without his overt approval. He is a god of mystery, and concealment. Prying deeper into his substance is quite likely to be against his nature. He'd HAVE to act if he found out.
-Studying the Chaos gods(including Hashut and the Horned Rat) is Dark Magic. We already know what shards of their power are - Daemons.
-Studying ANY major Human Order god is fraught. They have many, many means of making their displeasure known, and this will have further impacts on both our God and organizations. Whether they find out is another matter of course, but the step where you acquire the imprint is a location or object by definition imbued with their attentions.
-Studying the Dwarf gods is worse, because they definitely have very clear views on copyright and thieving, and while they aren't interventionist, if ANY dwarf ever learns we did it there'd be very few that would hesitate to carry it out anyway.
-Studying the Elf gods is a maybe, to my knowledge, most of them are non-interventionist, acting only through the elves mantling them. Bit hard to get our hands on some though. Maybe the Phoenix Crown has some Asuryan juice. And there's this Vaul holy site we'd get ritually sacrificed on if we get caught breaking into, in an high energy environment I'm not sure the Vitae would survive.
-Studying the Orc gods is another maybe. They're powerful as hell...but they're fundamentally very Orc. Not like this is our first rodeo stealing from them, and while they PROBABLY won't be doing anything particularly novel to us, they got Waaaghs for that.
-Studying minor human gods might be a thing. Their retribution is limited, especially the proscribed ones, though that is not to say its non-existent. We can get super cursed. However, bits of their power are few and far between.
-Studying spirits might be another thing. I refer to the Apparitions, Ghosts(as in, legit, free-range lingering spirits, though finding any ghost in a place that's not soaked in enough Shyish or Dhar to force the Vitae to react would be challenging), and possibly the Fae. This is quite relatively safe, because the beings involved can't really do much to us outside a limited range. Of course, this also limits what we can do with the copied essence.
TLDR - Try this trick on lesser spiritual entities first, we can at least fight those. Then go mug the greenskins again.