If the cross over is approved, they should put both model numbers and/or types on the breaker. I agree.
Siemens might be hesitant to do so for the same reasons I am digging deep into this issue - liability and professionalism.
Or maybe they are trying to sucker you and your client into paying for a panel replacement that's not needed. I would not cast such aspersions were it not for the fact that Murray and Siemens breakers of the last dozen years at least are
identical. I defy anyone to tell me which is which with the labels peeled off. So again, whatever reason they have for obfuscating this fact, it can't be very above board.
I'll put it this way: if for reasons of liability and professionalism you're reluctant to put new breakers into a very old panel whose connecting lineage is hard to trace, I might agree with you. But if you were going to be happy putting recently manufactured MP breakers in there, and you're reluctant to put recently manufactured Q breakers, that makes no sense. Because trust me they're the
same breaker. (That is, it makes no sense for reasons of liability or professionalism, as opposed to convincing an inexperienced AHJ.)
With that said, thanks very much for posting that documentation. Haven't had time to look through it but hopefully it proves what I'm saying, and will help people with persnickety AHJs.