I'm not asking anyone to do it necessarily, but I am curious if it is possible. I'm a software engineer and would love to give a crack at a backport, but would love to know about any potential problems

It may be possible for this specific project in the future, but not right now.
Fabric Loader, while it is version-independent, does not have mappings nor any dev-tools for 1.12.2.
Forge might be a option, if you are really dedicated, but it would be a lot of work.
Maybe it could be possible for Liteloader on the client, but again it would be a lot of work because of the differences between versions, with many of Lithium's patches only applying to newer versions.

Thanks for the fast response! Some interesting things to think about there!