even then Libreoffice isn’t good enough for half the staff in my accounting firm because it lacks certain features for now.

The worst part is where some functionality breaks in a document bigger than a holiday card. I mean formulae vanishing.

I think OOO around year 2009 was very stable and without such annoying bugs. But I haven’t tested it there TBH.

Seriously, feature parity is a dead end. If there were a cross-platform office suite that would at least support the absolutely necessary things with a format not much more complex than org-mode, big documents (300 pages without degrading performance) and UTF-8, it would be fine. I think. That format can even be XML-based, just … why would you have vanishing objects in a document past their certain number? Do they have an unsigned byte counter somewhere?