I wish you had been there to get this into the sriptwriters’ heads because it’s totally plausible without massively restructuring the movie!
I do agree it’s rather ambitious to have it come across seamlessly with what we have to work with. There might be a couple of those ideas that could be implemented to just give a slight implication of a larger effect for Finn. Even what we’ve got already for Jannah helps a lot already.
I would say the line from the “I like it” lady about there being more defectors would be nice, except… it just doesn’t mesh with the joyous slaughter of stormtroopers that happens throughout the movie. Or, maybe we could couch that within Finn’s line, “I didn’t know there were others.” As though his next line should be, “Oh, shit!”