Well, after the 100th episode that semester, maybe you should have had an intervention with your cousin.
More seriously, she "was coerced but not forced, but it was definitely not wanted" is very ambiguous. Keep in mind that the boys in question are ALSO "somewhat naive", and not mind readers (especially after a few drinks). To a teenage guy, there is a major difference between the girl saying "I'm not comfortable doing this" versus "No, I don't want to, I'm leaving" and her getting up and leaving. Statements like "I'm not comfortable" or "I'm not sure" are taken as invitations to continue making out until she goes along.
I didn’t say it happened hundred of times with my cousin! ;)
But I agree. The guys are immature and excited and drunk, and it’s hard for them to feel the exact difference between being seductive and coercive.
So these things will happen. However, the original question was, is a girl,safe at a frat house party, a house based on partying and getting some. She would be safer just dating a guy she met on campus.