If this wasn't Thibault, I would have believed this as another implausible project by some bro who rode the train twice in his life. I wish them good luck but can't really that much, being in another country , Ro, with even worse train situation :)))

A few more insights I got in a reply in another thread: https://jonworth.eu/sncfs-half-hearted-effort-to-support-international-night-trains-in-danger-of-hitting-the-buffers/

The usual politics and indifference: SNCF is unable to create a ticketing system+frontend clean enough that they can fix and integrate easily to sell cross-country tickets ("Une erreur c'est produite" has been the motto of their user frontend for 20 years already), other technical details are even more preposterous:

ÖBB uses a leased Siemens Vectron locomotive for the Nightjet to Brussels, but that option is not open here – France is pretty much the only standard gauge European country where Vectron is not approved to run.

Mostly solved with the help got here: https://discuss.kde.org/t/amarok-how-to-recover-statistics-database-lost-in-transition-2-9-3-x/32573 from Tuomas Nurmi:

According to amarok - Debian Package Tracker, only 2.9.0 was ever packaged for Debian. That one was still KDE4/Qt4 based, so it is possible that the embedded mysql/mariadb database is at ~/.kde4/share/amarok/mysqle/ and it could be copied to ~/.local/share/amarok/mysqle and everything’s there. There should have been an automatic migration from KDE4 paths, but at least I haven’t tested if it works during this decade. (Or, might also be some Debian-specific issue.)