So what you are saying is that my decision to stop paying attention to Type-Moon is a good one because rules are only there to show off how cool/special something is by breaking the rul. Ugh, the worst type of setting because it basically means there will always be an exception for everything.
At the heart of the setting, Magecraft has pretty well defined rules that almost everyone follows just the same. It's just that, every Mage alive is doing all they can to get past Magecraft and discover real Magic, which has no rules on it at all because it's Magic. And the stories we get are about the interesting characters, the ones who come closer than most to succeeding. You can safely expect most things to work the same most of the time, but that almost every character we follow will have one thing special about them that breaks the rules.
Funny enough, I say most because of Rin and Waver, a pair of fan favorites who's special thing is just being good mages. Rin has a strong bloodline and a lot of natural talent and a magical core that might even be special itself, but in the end she never does anything that breaks any rules, she's just really really good inside of them. Waver has a powerful mind, in his introduction scene proposing some revolutionary idea, then successfully stealing his way in to a Grail War, but lacked in power and didn't really pull off anything impressive other than entering the war itself. Many of the other Masters we see in the various shows don't break any rules either, though they are all pushing their quirks as hard as they can in rule breaking directions...
But yeah, just about every main character is a main character
because they're breaking a rule. If you're not in to that, avoid pretty much the whole thing. El-Maloy Case Files might still interest you, but the rest is all about the special people.
Would Taylor have some kind of anti-Foreigner alignment due to being the one who orchestrated the death of the Warrior Entity?
That's one of the biggest "how do you want to interpret it" things in the very idea of the Worm/Fate crossover. I think Scion is an easy fit for an Alien/Outer God, and therefore Foreigner an easy class to justify. Because the difference between legend and actual feet is less important than you would think, if Taylor gets an anti dragon special for her success against Lung she should definitely get a type advantage against other outer gods and their avatars.
On the other hand, I think the first canon Foreigner was Abby? And we're sorry unlikely to ever get there, so I doubt we'll see one in this story, but I would still like to read James' thoughts on the issue.