Ideally, VBA macros should just work in VBASupport mode. However, this ideal is very far from completion. So the only advise (beside the “rewrite using LibreOffice own API”, which would be obviously unrealistic for a person who doesn’t know how to write macros at all, and who uses someone else’s very complex macros) would be: if these macros don’t work with the compatibility mode enabled (i.e., in a Basic module having Option VBASupport 1
as its first line), then you only can report bugs for each failing construct, one by one, and hope that by year 2100, it becomes usable.