Given the fact that there was not much interest in the website in the last years
Speaking for myself, this is because it used to be a wiki and now it's a real website.
and Markdown is something each of us can write easily.
Agree, but also so is HTML, which gives much more control over layout/structure/appearance.
After all, if we want to change the backend of the website and/or replace it by something static or generated, let's do.
I'd be interested to working on this, but unfortunately except for using Flask a few times, I don't know much about using Python for making websites. Most of my experience is in JS/Node with stuff like NPM, Express, Webpack, Vue, etc. and I don't know whether other developers are comfortable with this kind of tech stack/tooling, or if it's even supported by our web host for the backend stuff.