Not able to input polish characters on OSX - alt capture?

I am not able to input polish characters: 偶, 膰, 贸, 艂, etc.
They are normally typed using alt+letter, so you get 贸 by typig alt+o
As other regional chars work correctly, the issue here is with Collabora capturing right alt for shortcuts, and then doing nothing with it - is there any way to stop this behavior?

EDIT: I know it鈥檚 strictly Collabora, not Nextcloud - as this special chars work normally in pure nextcloud (in filenames) or pure text editor.

EDIT2: This is not an issue on Windows, only OSX