The Ren'Py language is based on Python. It's a subset of Python that also has features not present in Python. Python programmers would definitely be frustrated and disappointed to learn that it's not just an engine that you program in Python, as Wikipedia would have you believe. There's a learning curve when you figure out all the Python things that Ren'Py can't do.
At best, you could maybe call it a Python-based API. If it looks like a language and works like a language, it's probably a language.
https://en.wikipedia.org/wiki/Ren%27Py
At best, you could maybe call it a Python-based API. If it looks like a language and works like a language, it's probably a language.