Project information:
Name: OpenTeacher
Homepage: OpenTeacher download | SourceForge.net
License: GPLv2
PLEASEEE!!! It’s not working on linux anymore… 
It has a problem with the wrong version of python, I think.
This software hasn’t had a new release in, like, 8 years now? So I suppose there is no one maintaining it anymore.
Also, its still requiring Python 2, which itself is not maintained as well anymore.
This would probably need a maintainer first updating the code, maybe even rewriting it. Not something Flathub can help you with unfortunately.
You could in theory write a manifest building the app and a Python 2 installation for personal use, but I highly doubt it would be permitted on Flathub.