I know this response is crazy late, and for that I'm very sorry.
Given that the toolset for was originally built and optimized around Vanilla WoW and 40-man raids, I think I'll be able to back-port some of the addons to work properly for private servers. Unfortunately, the software had to evolve as the game evolved, hence the failure of it to be backwards compatible. But I'm going to try to set aside a day or two in the coming months to look into this.
My time is extremely limited these days, which complicates the timeline.
But I want you to know that your concerns here regarding playing on private vanilla servers is acknowledged.