Maybe installing the missing plugins (kontakt, omnisphere) from scratch?
GP asking for activation seems logical to me: it’s not the same system. If you’re not going to use GP on your old system, then don’t forget to deactivate GP: that way you regain an activation.
This is a mistake. You do not want to be loading Intel versions of plugins when you run Apple Silicon (even with Rosetta nit withstanding). The reason your Intel AUs are working is because Apple automatically runs Intel AUs under Rosetta.
Yiu should explicitly install Native or a universal version of each plugin you want to use
See this blog article we wrote four years ago addressing this issue