C12 also runs very stable here. Since the last maintenance update it only crashed once, and that was in a busy project when trying out new plugins. However, I think there are still some smaller annoying bugs, which need to be fixed.
I can confirm, that crashes mostly have to do with 3rd party plugins (which are out of control of Steinberg). But I am also convinced, that SB have to make sure, that even if a plugin crashes, Cubase has to make sure it runs, no matter what. Thats why I made this FR not long time ago. Would be nice if you could support it by giving it a vote, if you think the same:
@skijumptoes @absolute-music @jazztom @Elien @somecomposer @inthefold