Hello,
After an exhaustive search, I eventually found the Japanese insulation specification, referenced by the various online Chinese magnet wire distributors. Since the text was in Japanese, I translated it (with an online tool), edited it to fix the translation mistakes, reformatted the tables, then uploaded it to a git repo. I hope you find it helpful in your own projects.
If you know of any other specs for enameled wire, please post some links here.

Thanks!

 

I use the NEMA standards available from manufacturers, such as this one from Essex.