OC27, unfortunately the CIF database is organized by who filed the transfer approval paperwork, which is almost always the destination school. So unless you have the name of a kid, or the name of his new school, it would be an impossible task to identify all the kids who may have transferred out of the league.
Secondly, this is the time of year when schools perform their due diligence on things like academic eligibility, actual changes of residence, etc. Whether you like or dislike individual Trinity League schools, they are all very good at this. It would be unlikely that any of those six schools ever gets busted for using ineligible players, as happened last year at Los Angeles and Augustus Hawkins. With Week Zero games scheduled for Aug. 25, I'd expect the tidal wave of submissions and approvals starting around Aug. 10.