I believe (although I won't claim to know details) that Rosetta is unable to handle the code our self-hosted backend emit. I don't know whether it's related to the machine code or the Mach-O object, nor do I know in what way it breaks. Feel free to try it out of course!-- my understanding could be wrong.
Next time you try Rosetta and it fails can you open an issue with the error messages? I think this task would be perfect for o3 to work on, you basically have to browse hundreds of issues on GitHub and find other people that got into the same problem