If I'm enrolled in a CSU during the fall, and a CC during the spring, what will a UC see?

Assuming those are lower division courses, you should be fine as they just round them all out to 70. However, I’m never quite sure if having a ton of non-CCC units makes them look somewhat negatively on it. I’ve kind of heard conflicting things about that.

But be that as it may, you will only be transferring 70 LD, despite how many LD units you actually have. Then add any upper division on top of that. There’s where you need to calculate unit maximums. Some cap at 80.