The prevailing idea seemed to be that if you wanted conversion of Word documents, let's say to screenshots, to match properly in all cases, the only way was a dedicated (or virtual) machine running Windows+Word and some VBS to automate the conversion.
I don't know if this is still the best way. LibreOffice has came a long way for sure, but still doesn't reproduce Word's layout perfectly (which is still the expectation).
Some differences in rendering or printing would be acceptable - what is not acceptable, however, is unintended corruption of existing documents.
E.g. if I open a word document in libreoffice (to do e.g. review and commenting), save it without any changes to the layout, then I'd expect the original author to have the same document layout as before... and that is not so. The same applies to LibreOffice Calc - opening and saving the document produces changes.
Can't you just have a unit test that verifies that reading and immediately writing a document should keep it completely unchanged, except possibly for metadata?
I don't know if this is still the best way. LibreOffice has came a long way for sure, but still doesn't reproduce Word's layout perfectly (which is still the expectation).