Just a quick progress update. The new campaign has helped me spot quite a few significant bugs. It's surprising how much you can play and still miss fairly large problems
The campaign is also highlighting missing areas, such as forgetting to add code for refuelling ships in hangars, plus I've been fixing the AI as (fairly minor) problems become apparent. I still have some areas to add to the AI, such as attacking and/or invading colonies, plus more options for starting NPR design themes. In general though, the AI seems a lot better than VB6.
Increments are still MUCH faster than VB6 with sub-second increments nine years into my current campaign, which has a large player race and two NPRs.
In terms of major functional areas, they are 95% done (probably higher) with Diplomacy remaining the area that needs the most work. At some point I plan to start a test campaign with multiple NPRs in Sol, so that will force me to tackle the Diplomacy AI code
I'm still not ready to predict a release date, as a lot depends on my available free time and enthusiasm, but I am starting to see light at the end of the tunnel
Just hope it isn't an oncoming train.