I do feel those are solid points, but I think there is still some disconnect. I think those are logical reasons why they could trust R2 and not wipe his memory, it is all only assumption, really. We have to assume this stuff rather than the story telling or showing us that. So to me, I feel like R2 should either be in on it or he isn’t.
Let me suggest four options, in this case:
Option #1) Have R2’s memory also be wiped in the end of ROTS. He can’t say anything because he doesn’t remember anything.
Option #2) Have R2 be in the room with Obi-Wan, Yoda and Bail when they discuss their plans for Luke and Leia. He doesn’t say anything because he is aware of the plan and knows not to say anything.
Option #3) Remove R2 from Padme’s birth scene. In this case he at least would not know Leia and Luke are brother and sister. He doesn’t even initially know Padme had children. He probably doesn’t know Anakin is Vader so this is arguably the biggest secret R2 keeps.
Option #4) Leave it as is. Maybe he either thinks there is nothing worth saying or he thinks it’s not his place to say anything.
I don’t want to change things just to change things, but if we can make changes that help create a more consistent, self-contained story, then I would like to do that. Another way I like to see is that I would like to make it where you can watch all nine movies and not be left with too many questions, like who was Sifo-Dyas, why didn’t R2 ever mention what he knew, how does Leia remember her mother, etc.
If anyone is in favor of a certain option I would love to hear it!
Regarding Obi-Wan, another line I forgot to mention was, “He [Owen] didn’t agree with your father’s ideals, thought he should have stayed and not gotten involved.” I don’t really think this is a big deal, it is either a part of Obi-Wan’s lie or he could be again quoting Owen’s own assumptions based on the brief time he knew Anakin.
Two more things, another edit I would be interested to see people’s takes on is Luke & Leia’s conversation about their mother(s) in ROTJ. I know some editor’s on here have already tackled it, other’s haven’t, but I think it would be cool to see people’s interpretations on how it should be altered. If Padme dies in 3, I think most people agree that something should be done with that scene.
Finally, I’ve created a small wav file of JEJ saying “your mother”. I attempted to alter the audio to sound like Vader, but I wasn’t sold on it. I’m also worried about him saying it too quickly, but may it could be slowed down? If someone would like to have a go at it, feel free to.
https://drive.google.com/open?id=1XsiK4YZI8ae5oUK52R7L8wBxp7ecDQQX