I’d like to give RM8 a try, which would involve importing a GEDCOM from Heredis. Can I just import it directly or is there a better way so that I can avoid as many problems as possible? I have a copy of FTM 2019, if using that as an intermediary is recommended
Use GEDCOM for both of those versions.
I have imported Gedcoms from Legacy, Brothers Keeper, My Heritage, Gedcoms from GRAMPS which have been converted from Excel CSV Spreadsheets and many others and RM8 has accepted every one of them. Exporting Gedcoms from RM8 and importing into other genealogy programs works just as well.
RM8 mac does seem to import gedcoms fairly well but a gedcom sent back to FTM 2019 is very different from what came in.