I watched that video yesterday too! I really like his perspective. I’ll talk about the lineage stuff at the end.
I think simply referring to “First Order spies” in the crawl would be the simplest thing to do, and also be a nice parallel to the mention of “Rebel spies” in the crawl of the original Star Wars, too.
I don’t think that idea and the idea of him representing “hope” are two separate things. I don’t really think TLJ drops the training a new generation of Jedi angle either. Yes, Luke doesn’t want to train more Jedi, but Snoke nor Kylo know that, but can you really blame them for thinking that? That’s what we thought would happen before seeing the movie too.
Snoke: The seed of the Jedi Order lives.
This is clearly still on Snoke’s mind. He’s still afraid that that “seed” will grow. I can imagine that after Ben destroyed Luke’s temple and most of his students, instead of being happy, Snoke was probably mad at Ben for not finishing the job and killing Luke (that’s sort of the nature of abusive relationships, the victim always does something wrong in the eyes of the abuser). This probably haunts Snoke for the next six years, that Luke could return and have more Jedi with him, and this is also why Kylo Ren is so desperate to find Luke in TFA.
So when Snoke finds out that all of his worries have been for nothing, and that Luke wants the Jedi Order to die, he is euphoric. You can’t really blame him for being afraid of the Jedi’s return, especially after an untrained girl had just defeated his apprentice and went to go find Skywalker. But the truth turned out better than he could have imagined. And this new found excitement is probably what made him so blind to Kylo’s true intentions. Everything was going right, the New Republic is in disarray, the Resistance is in its death throws, Luke, the last Jedi and his greatest enemy, is just waiting to die, and the galaxy will be his in a matter of weeks. I definitely think his over-confidence was warranted, and the surprise of finding out Luke wanted to die likely is the reason Kylo was able to get away with his trick. I think the whole thing works really well.
I do think this whole idea would draw even more comparisons to Luke being a King Arthur figure, with the galaxy being Camelot, Anakin’s saber being Excalibur, and Kylo Ren being Mordred, who is sometime Arthur’s son and sometimes his nephew depending on the version.
Maybe a change that could help this idea would be to try have people to only refer to Leia as Princess, if possible. I think that would be challenging though.
Sort of like the first conversation between Poe and Lor San Tekka. Poe calls her general, but Tekka says something like, “General? To me, she’s royalty.” Poe then says something like, “Well she certainly is that.”
This could work in your idea’s favor, but the way this conversation goes makes it seem like most people don’t necessarily view Leia as royalty anymore beyond being a ceremonial thing. Maybe you could cut out Poe’s line? I don’t really see where other changes could be made to imply this idea besides the opening crawl, though, which could just make it feel disconnected to the rest of the film. Ironically, I think “Heir to the Empire” could work well as an alternative title for this film with that idea in mind. I just don’t know how feasible the idea is if you wanted it to be a major theme.