D24, the summer after her junior year, took 2 college classes, 1 senior year required high school class, two weeks of residential programs, and some short term theater projects.
I thought it was too much, but she had reasons for why she wanted to do all these things.
In terms of managing things, getting all her schoolwork done while in a residential program at a college was very difficult. Some professors do things like assign homework on Monday, due Friday at noon. The exam might not be open online until Wednesday and you only have a certain smallish time frame to finish it. Some have multiple hours of pre-recorded lectures that you have to watch.
There is something quite amazing about being able to delve into a residential experience and just go all in on it. Having to juggle 5 balls at the same time changes things significantly.
Long story short, D24 got her only B of the year that summer and wished she had only done one week of a residential program. She doesn’t regret it overall, because there really were good reasons for all the things she did.
If you are able to focus only on COSMOS, you will get so much more from the experience. Perhaps contact a UC directly for clarification on the FL situation (email so you have something to show your counselor), then circle back around with your counselor as well after you talk to a UC to make sure everyone is on the same page. Sometimes on paper minimums and the expected minimums for successful applicants are different.