I recognize that this is kind of a big ask, but I am wondering if you would consider an alternative plain text syncing or storage option. I understand that Inkdrop uses a JSON schema currently, so the metadata attached there would be lost. I think this would be a fine compromise as long as it was communicated to the user (or you could still have the JSON as pure metadata).
The advantage here being the option of editing notes in other places, and transferring them in a more universal way without an intermediate import/export step.