Hi !
to turn back mobile editing on web you just have to do this :
For onlyoffice document server 7.0
search for this :
isSupportEditFeature=function(){return!1}
and replace it with:
isSupportEditFeature=function(){return 1}
inside these 3 files ( replace the path of document server by yours)
sudo nano /var/www/onlyoffice/documentserver/web-apps/apps/spreadsheeteditor/mobile/dist/js/app.js
sudo nano /var/www/onlyoffice/documentserver/web-apps/apps/documenteditor/mobile/dist/js/app.js
sudo nano /var/www/onlyoffice/documentserver/web-apps/apps/presentationeditor/mobile/dist/js/app.js
restart your nginx and sometimes you have to clear the cache and cookies of your web browser