Roo, I’m so glad we did this analysis of Roma as I definitely think I understand it better than I did when I saw it in a movie theater. I loved it then. Appreciate it more now.
Your take here, for example, really crystallizes how in some respects it does differ from conventional Hollywood fare, yet works as a story. Sofía changes more than Cleo and your point about Sofía’s upper middle class standing gives her more room for personal agency. Both are reactive, a no-no in Hollywood development circles re protagonists, but that’s kind of the point of the movie in a way: women surviving in a patriarchal society.
As to your last point, the fact the year in question was one of such upheaval in Mexico City is also noteworthy. I try to imagine the movie without that heightened societal dynamic… and you not only miss out on some memorable scenes (the shoot-out / riots / Fermin with a gun drawn on Cleo), but also how the larger civic upheaval mirrors the more intimate personal upheaval confronting the two lead women.
Which leads me to my big takeaway: Write the story the way the story needs to be told. But always in service to the story, not just to break supposed rules or be cute. If the story speaks to you to be told this way and you are convinced that is the way it must be told, then go for it. Get some feedback and see if it works. You can always revise it if it doesn’t work on the page. But at least give your original vision your best shot.