Hi. Sorry for the delay in replying.
On your behalf, I asked the question over in the Flare Slack community. I just got a reply (today's June 13):
Apologies for possibly resurrecting a dead thread but our company has this exactly problem and were told that "it's coming" but weren't given any timeline. When we asked about beta testing the feature (because ALL of our "stuff" is in RH2020) we were told that wouldn't be possible, the feature wasn't fare enough in development yet. When starting an import from RH, the RH2020 projects (*.rhpj) aren't selectable.
So sorry to report that there's no solution for the time being.