You might get a better response from the other group…
This group was originally created for questions specifically about DITA-OT, and your question certainly is that. But in practice, over the years, this group has seen very little use compared to the other one. I think the only reason why this group still exists is because everyone has a Google account while not everyone wants to create a separate Groups.io account.
Nevertheless, I would be interested in your solution. I'm in a similar situation: I'm stuck on DITA-OT 1.8.5 because I'm dependent on the Moldflow plugins to produce .chm files with support for context-sensitive help links. Those Moldflow plugins also use resourceid.