Note that another project did the same with a more focused approach on a limited set of games to support: https://aarongiles.com/dreamm/
It's closed source unfortunately.
Very cool to see more people getting things running in the web. I am still using BoxedWine on my site at the moment but I could see one day moving to Retrowin32. 64-bit apps would be the holy grail though.
He talks about rosetta not implementing nested pointer enter instruction. For newer apps, there is also the issue that rosetta doesn't implement AVX and newer instructions, due to patent issues
I'm surprised this hasn't been done before. Good luck to the author, it's a noble project!