My son goes to Chico State, I know there are international students on campus. Their web site says they welcome more than 500 of them. Perhaps they don’t participate in your program.
http://www.csuchico.edu/graduatestudies/prospective/international.shtml
Timber Creek is known as The Zoo for a reason… and definitely attracts more spirited students - and has since the 1970s. .
Both (Fullerton and San Marcos) have fraternities - therefore there are parties but, the communities of Fullerton and Oceanside/San Marcos are much less tolerant of college parties than Chico. I’d be surprised to see a complex that lively near campus Fullerton or San Marcos. Honestly, i don’t know them as well as I do Chico. If you have to pick between the 2, Fullerton is a larger, more established campus.
Not on your list above but, CSU Sacramento will probably fit your bill too - especially since you;ll be 22. There’s no shortage of live music/nightlife/pubs in East Sacramento and Mid Town areas.