Is she still interested in engineering / comp sci ? There is a page called Big Door / Little Door for UCLA that explains how competitive engineering (and CS) are at UCLA. Berkeley is no different, it is ranked #1 for some programs so they get really, really impressive candidates. UCSD is likely no different and without direct admit, you have to take non-honors classes and hope your GPA is higher than others.
She has fantastic stats and likely a very high UC GPA. It is very unlikely they have 20 Eng/CS openings.
I think she may be too qualified, too in the know being at a top school to be admitted to something like COSMOS which might really want to attract less traditional candidates, especially women.
I think the idea of a 10 AP class person attending CC is irrational. Like many, she would waste at least a year waiting to transfer with no real classes to take (she will be done with CC STEM classes in less than a year). The quality of the classes would be far below what she had in a competitive high school, unless she attends the top CC in CA. So the I won’t attend UC-R because I would rather go to a CC, no … no … no … You could easily end up being an OK CC student and transferring to UC-R and still being behind, rather than being UC-Rs top percenter. Peers are important, interesting classes are important, etc.
UCI is nationally ranked. Who cares about COSMOS, just check another box on the UC application. As a non-CA resident, I don’t know much about other schools, but I doubt they are awful… Cal Polys may also be good contenders.
Without being emotional about it, a balanced list of reaches (Stanford, Caltech), matches (UC-4+ top schools), and safeties that she actually likes, will give her a good choice of schools by spring. One will work out, and it will be good. One thing you can easily see here on CC or by talking to parents is that it is rare to get exactly the acceptances that you want or that you think you deserve, but if you keep reasonable options open, you can go to a great school (and I really think any top 100 USNWR is likely a great school, not just the top 20).
If she wants to trade Cali for a cold climate school, that opens up a lot of other options who would probably be thrilled to accept her and may even offer significant merit aid.