See the details in https://bugs.winehq.org/show_bug.cgi?id=52213 and https://gitlab.winehq.org/wine/wine/-/merge_requests/1088, also https://gitlab.winehq.org/wine/wine/-/merge_requests/1503#note_17119
As far as I understand, what's happening in bug 52213 is that threads that are killed while in glibc die noisily, by triggering a Wine segmentation fault. But this doesn't inhere to condition variables, it only happens after threads are killed for one reason or another, and it doesn't actually have any adverse effects besides printing some extra messages to the console (I don't even think it triggers a winedbg window?)
In that case it doesn't seem to me that condition variables are actually broken, or really that anything is. The extra messages do seem undesirable and misleading, but they're a consequence of killing threads, which I think should be avoidable in most cases anyway.
Or is there some other aspect of the problem that I'm misunderstanding? Do condition variables actually misbehave in some meaningful way?