Now, when I try to re-install it with synaptic, I always get a “broken” package (which refuses installation).
how to re-install libreoffice in Debian 9.4? (my fault: it was uninstalled when I installed gdm3???)
Without detailed error messages and your consent to use commands in a terminal, hard to help.
Manually resolved, according to instructions from:
Sorry, to bother.