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.)
Amarok: how to recover statistics database lost in transition 2.9 -> 3.x
Some time ago (I think january) Amarok, was updated in Debian, from 2.9.x to 3.x (now it is 3.2.2). After the upgrade Amarok no longer showed the things from the database (lyrics, listen counts, etc).
I would like to restore the statistics database but I did not find the steps. Could you point me to the right instructions, or provide some advice about how to work on this?