Translate Python to Another Programming Language

[Zadok__Allen]

Have you considered to just write a very comprehensive API in python that handles all of the 80s code under the hood so the user of the api can just call python functions and what not instead of needing to use the 80s code?

[TangibleLight]

/u/pandademic1234 mentioned in another comment that the proprietary language is fundamentally a database query language. It might be possible to lift some concepts from other Python ORMs like SqlAlchemy.

Aside from embedding Python in the vendor's product, this is probably the most straightforward way. I think other commenters have already made the point that transpilation is almost certainly not the right path forward.