tl;dr: That. In the TeXmacs’ github org.
I finally got around packaging the thing as a plugin, adding minimal documentation, some (preliminary) tests and fixing all the stuff that made the thing basically unusable beyond my (first) use-case. Now I can use it for my current project and hopefully others too.
There are TONS of things that could be improved, with md->tm being the biggest one. MRs welcome!