When i installed UB 19.10 I selected for the full install which included LibreOffice.
When I go Settings (in Budgie, not LO) > Language & Region and change the language from English to Dutch, after restarting the session, the shell is in Dutch.
However LO is still in English and there is no option to select Dutch, English USA is still the only option.
With Ubuntu Server, LO takes over the language from the OS and becomes Dutch as well. Just wanted to point this out.
As LO does not guide users how to get other languages and even spell checker dictionaries (for this it links to the site, where very few language extensions can be found) it took me a while to Google and eventually via a different forum I found the instructions here that work with UB 19.10:
See the French example.