Because various Profile reporting requirements are based on individual school policies that are subject to change at any time, the timing of my past experience means little. My consistent message in this thread has been, “this is what I learned, and my recommendation is that a student (perhaps with a parent) who owns a 529 account and is applying for need-based FA now or getting ready to apply should make an inquiry to Profile schools being considered to ask how this account should be reported.”
You are making this a lot harder than it needs to be. Within the past 15 years, when the FAFSA methodology had/has student-owned/custodial 529 accounts reported as a parent asset, there were (and could very well still be) some Profile schools that consider these accounts to be a student asset. This is based on my personal experience. If you are so desperate for information on the frequency that this happens and which schools currently adhere to this policy, I suggest that you do your own research. You can use this table as a good starting point:
CSS Profile Participating Institutions and Programs (collegeboard.org)