I am analyzing the coverage of TTF or OTF screen fonts and discovered that the version of NimbusSanL-Regu.ttf I had obtained years ago was an early fork of the original, adding Cyrillic glyphs. It also changed the fontconfig name to ‘NimbusSanL’ I only realized a couple of days ago that where fontconfig is looking for possible aliases of a missing font it looks for ‘Nimbus Sans L’ not 'NimbusSanL (e.g. when in a graphical terminal)
I have now found that (a newer version)
The old font was NimbusSanL-Regu.ttf along with bold and italic variants. First, as the superuser I removed those.
Stil as the superuser I then installed the new otf files, NimbusSanL-Reg.otf etc.
As a normal user, "fc-match ‘Nimbus Sans L’ now finds it.
I then opened lowriter on a new text file listing all the codepoints in the new file, ran ‘select all’, and then tried tto change the font to ‘Nimbus Sans L’ but the previous ‘NimbusSanL’ is in the font list, not the new font.
Closed the document and libreoffice. Ran fc-cache -f -v as normal user. Opened the document, retried but still the old NimbusSanL not Nimbus Sans L is listed. Closed libreoffice.
Ran fc-cache -f -v as the superuser.
As normal user, deleted the previous odt file, opened the text file, selected all, but no change in listed fonts. Did not save, closed libreoffice.
I assume there is some sort of cache (based on the help prompt showing up only on the first time I open libreoffice each day) ?