When I want to insert or paste an emoji in Doc, Sheet or Presentation, it insert an empty square like this : □ instead of the expected emoji. Of course, emoji work fine on all other installed apps. I also noticed the Apple color emoji font is not listed in the fonts list while it’s installed and working on my Mac.
OS version: Mac OS Mojave 10.14.6
App version: 7.0.1 (531) x86
Downloaded from: ONLYOFFICE website
Hello @Kroc
We have checked the situation and we added a bug to internal tracklist (internal number - 56496). We have started working on it.
Hi @Alexandre,
More than one year later, I’m now running OnlyOffice 7.3.3 (538) - Apple Silicon on Mac OS Monterey 12.6.5 (MacBook Air M1) and this bug is still there. 
Hello @Kroc
Sorry for the length of the situation. We’re still working on it. I will update this thread when we have something to share.