Hi
the installation instruction on https://www.libreoffice.org/get-help/install-howto/os-x/ needs a bit of love and care.
This next part seems incorrect. Or, at least it is unclear to me:
“If needed, you may now download and install the language pack(s) of your choice and built-in help by downloading the .DMG file of your choice. The installation steps are the same than the ones described above but you must have downloaded the main LibreOffice DMG file at first.”
Dragging the language pack into the applications folder does not result in a new interface language, and neither does this result in an extra option in the “preferences/language” menu.
Disclaimer: no Mac head here.