Always a problem sharing documents between the various office suites
and the more complex the construction the more challenging it is !!

Good to hear Calligra seems to do the job for this particular document
but you may find others don't fare as well - question is when you save
in Calligra does the user with MS Office find it renders correctly ?

FWIW - there can be the same problems between the various MS Office
suites too !

Ultimately the safest bet is for all collaborators having identical
office programs - and here is how the MicroSoft money machine keeps on
rolling