Hmmm, come to think of it, it's true that the formatting is not always perfect when coming from Word files, etc. I didn't even know Onlyoffice existed.

Looking at their github, I don't see a gpg public key file and a checksum file which I usually prefer to have before putting anything on my computer. Apt-cache on xubuntu doesn't seem to show that it's part of the repositories.

I'll try to find the verification files somewhere. If you know where I can find them, please let me know.