(1) What I also love about Rose is that she is so utterly distinct from Rey, and the movie narrative doesn't make her story about Rey in any way. (Yet -- hopefully, IX doesn't go into "Rose-Finn-Rey love triangle" territory, or create a jealousy dynamic like the TLJ novelization did) Movies where there's such a limited number of main female characters will often juxtapose them in stereotypical ways: the Dream Girl and the Plain Best Friend, etc. But Rose IS different from Rey, from the start:
(2) for example, Rose realizes Finn isn’t who she thought he was and immediately acts on this new information, while Rey is the type to wallow in denial and doesn’t let go of her vision of Idealized Hero Luke for a while. There’s never a “Oh, you’re not like Rey in X way!” dialogue with Finn, we never get the impression that her primary function is as Finn’s love interest, her pain and feelings about the FO aren’t just there to make Finn feel manpain. And I really hope this continues in IX.
“Movies where there’s such a limited number of main female characters will often juxtapose them in stereotypical ways: the Dream Girl and the Plain Best Friend, etc”
^ oh yeah. It’s the “two girls to a team” trope, which polarizes two female protagonists and makes them “as different as the sun and the moon” (looking at you too, Westeros Georg) so that the general audience doesn’t have trouble distinguishing them, apparently. (mainstream media tend to do this with anything that deviates from *standard human being character*—which is invariably white, male, able bodied and preferably in a 20-45 age bracket). See: the blonde and the brunette, the Tomboy and the Girly-Girl, etc.
And Star Wars didn’t do this with Rey and Rose (also thanks to the fact that TLJ features a wider variety of female characters which allows diversity without forced or contrived polarization). They’re different, but not specifically each other’s opposite, nor their differences are deliberately set up to put them in a competition of sorts in relation to Finn:
“There’s never a “Oh, you’re not like Rey in X way!” dialogue with Finn”
You never get the sense that Rose’s entire appearance and personality was created as an “alternative” for Finn that is a complete 180° subversion of Rey. For example, she’s not the “geek” (a stereotype that unfortunately is often applied to Asian characters) to Rey’s lack of tech-savviness: they’re both geeks (in a good way, as in extremely competent with technology and engineering).
and they’re both (as you pointed out) idealists, though they react differently when reality disappoints them:
“Rose realizes Finn isn’t who she thought he was and immediately acts on this new information, while Rey is the type to wallow in denial and doesn’t let go of her vision of Idealized Hero Luke for a while”
Rose’s personal baggage is her own; her trauma isn’t a foil or an echo to Finn’s, or Rey. Still, it dovetails perfectly with the narrative and with Finn’s own character development, without losing its individuality. We’ll see how she interacts with Rey, but I certainly hope the narrative won’t pit them against each other or create artificial tension between them, especially of the love triangle-y kind (and I don’t think it will).