Yes : you can delete the language files you don't need in "Apps\LibreOffice\App\LibreOffice\Basis\program\resource".
That's what I did to reach 378 MB total.

The tricky part, though, is how to select the files to delete, among the ones you want to keep, as all the files are named "x...xCC.res", where "CC" is the Country Code (en, fr, ja, etc...)

For that matter, I used an exclusion filter in Xplorer2, to select (for deletion) ALL files BUT the ones to keep.

If your selection and deletion process was OK, then you should get 77 files for each language you kept.
(For instance, I kept English-US, French, and Japanese, so I now have 3 x 77 = 231 files remaining).

Hope I explained it clearly enough...

bibilapin wrote:Yes : you can delete the language files you don't need in "Apps\LibreOffice\App\LibreOffice\Basis\program\resource".
That's what I did to reach 378 MB total.

The tricky part, though, is how to select the files to delete, among the ones you want to keep, as all the files are named "x...xCC.res", where "CC" is the Country Code (en, fr, ja, etc...)

For that matter, I used an exclusion filter in Xplorer2, to select (for deletion) ALL files BUT the ones to keep.

If your selection and deletion process was OK, then you should get 77 files for each language you kept.
(For instance, I kept English-US, French, and Japanese, so I now have 3 x 77 = 231 files remaining).

Hope I explained it clearly enough...

Yes, thank you, bibilapin, your explanation was perfect. I managed to further reduce the size of my LibreOffice installation to 421 MB (keeping 4 languages). Still larger than OpenOffice (which only had 2 languages), but not by much.
Now I'm wondering if we'll have to do this every time LibreOffice is updated
If that's the case, then I'll probably move back to OpenOffice. For now, I'm keeping my "lightened" LibreOffice.
I guess we are not the only ones to have noticed that the full installation of LibreOffice (with all languages) is probably a bit too large for a pendrive. Does anyone know if LiberKey developers are considering releasing a lighter version of LibreOffice? It'd be most welcome.

The only problem is : every time we will update or upgrade LibreOffice (it means ? every month ?), all the job has to be made again ! It's not a solution.