I sympathise with the worry about long term maintainability. I will say I am willing to take on this task and resolve any ASan related problems that might come up in the future. I don't know how much weight you will put on my words, but there's that.
Sure, it's great that you are willing to do that. But note that it's actually an argument for keeping it as a separate fork that you have the responsibility to maintain, as opposed to merging it upstream where it becomes everybody's responsibility when making changes to affected areas. Considering that you have to rebuild the whole tree anyway, it doesn't seem too onerous to tell people "to do an ASAN test run, apply this patch and rebuild".
i am not very knowledgeable on this, but wouldn't it be better to always use native unwinding mechanism rather than wine's hack? i don't know if this is doable, but if we can make __TRY/__EXCEPT expand to SEH directives for PE and dwarf directives for ELF, then get rid of __WINE_FRAME, then we don't need ASan specific workarounds.
Sadly that's not feasible without compiler support.