Een wrote:
I would propose as a basic guidelines set:
- no punctuation for buttons and action bar messages
- always aim to improve consistency, never decrease it (if the developer mostly used ending punctuation in the logs, add missing punctuation in the logs; if not, don't)
- never change or add meaning to a string if you are not 100% sure (a mistake here is costly as it can propagate to other languages)
- for games, take the time to play and see strings in context before changing anything that is not just an obvious typo
- for games, when possible, refer to the game rulebook as a guide for style (but be aware that it's probably not perfect either).
Would that work? Other suggestions?
Should I make the warning popup show up at each change of a reference text (versus just for the first change currently)? Or would that be too annoying?
It would be too annoying.

I sort of figure if someone didn't read it the first time, will they ever? I also figure that anyone doing this on a regular basis should already know what that says.
You could add a line about capitalization that's similar to the game log punctuation, i.e. keep it consistent with what the developer did, unless it's an obvious breach of grammatical rules - not sure the best way to say that. The problem here is that sometimes it's a "style" and is OK to not be correct with the rules. Like resources could be capitalized and just not worry that it's not correct in English - it's a game. But if a proper noun were
not capitalized, that's just wrong. Plus being consistent. I feel like this should be common sense.
I would put that in the Guidelines specifically for English. (Edit: I mean at the top of the forum where the other is.) That's also a good place for people to ask more questions as they come up, and you can edit as necessary. Unfortunately some people may not see it there. It should be on the translation page.
Oh, you could maybe add that we don't have to take all the
him's and "neutral" them. I did send a private message about you changing that, just as information. I hope that's not a problem.