This is a common theme among Toyota Service departments with this car... and people genuinely believe they're going to put ANOTHER high performance BMW engine into these cars... it would be an absolute comical shit show for Toyota techs trying to discern and correctly troubleshoot between the...
If you're going through his insurance it most likely will be reported but as for Diminished value, at fault insurance will usually low ball the hell out of you as usual.
For best results, get a 3rd party appraisal by a professional appraising company that specializes in diminished value...
S58 Supra would be insane but we just need to go ahead and kill this idea because a B58 Supra is already directly competing with the M2... an S58 Supra would downright kill that market and, as previously mentioned, it makes absolutely zero sense for BMW to introduce their flagship M-line motor...