"A program that translates between high-level languages is usually called a source-to-source compiler or transpiler" from https://en.wikipedia.org/wiki/Compiler.
Yes, a compiler. The fact there's a note in Wikipedia doesn't change my view.
If you have a better reference I'd be happy to change my mind.
Not everything benefits from citation.
hmm I tend to be a bit skeptical about "ipse dixit"-like statements, but I think I got your point about compilers/transpilers :)
Anyway, the main point is to give it a name that is as informative as possible. If I read "transpiler" I immediately make the connection with the fact that it translates a high-level language into another high-level language (which is what prometeo does)- but maybe I am biased.
You'd need to know what both languages are to know what it does, and with that knowledge you can just call it a compiler.