PROGRESS REPORT
I'm obsessed with the idea of simulating a multiple-nations conventional start with NPRs. I'm almost able to do that.
The trick is to use SpaceMaster to create several other nations on Earth - you need to create them as NPRs with 0 bonus research points. Then close the game, open the database, and in the "Race" table, switch off the "NPR" column by these races, thus making them playable. In Aurora again, you can now SpaceMaster these races to your liking. I delete all TN industry, replace it by conventional industry (the AI is able to handle that no problem), replace all shipyards by one 1000-ton one, replace TN ground units by conventional units etc. Then close Aurora, and delete all ships associated to these NPRs in the "Ship" table in the database. Finally, switch the NPR checkboxes back on in. This leaves me with NPRs that have basic TN techs (which seems to be necessary for the AI to function) but due to other bottlenecks - conventional industry and almost no shipyards - they can't utilise most of them yet. From outside, this looks almost like a conventional start.
It seems to work too - the NPRs convert their industry to TN factories, they add slipways to shipyards, expand them etc.
I do have one issue though: they don't seem to be building any ships.
Now, when an NPR is generated, the game runs a ship design routine and populates the NPR with many ship designs. It even prebuilds some of these ships. However, when I replace the default shipyards by a starting, 1000-ton one, all of these designs are of course too big to be build. I thought I would just need to wait for the NPRs to expand their shipyards, but that didn't help. At this point, several NPRs have 3000+ tons large shipyards, which is enough to build their geo survey designs, but they don't do that yet. They also have <1000 ton large FACs, and they don't build them either. Aaaand, they have several PDC designs and again they don't build these (although this might be because they want to finish conventional industry conversion first, which they haven't yet).
I don't know if this has to do anything with the fact that I've deleted all their ships via the dabatase. It shouldn't matter, I think, but perhaps I broke the AI somehow. To confirm, I've started a new game, created a new NPR on Earth, left all its ships and industry intact, and advanced time for several months. They haven't started building a new ship, and I didn't have time or patience to test more.
Does anyone know more about how NPRs choose to build their ships? Do I simply have to wait some more years to have the NPRs in my pseudo-conventional game start building ships? Or is this hopeless, and I broke the AI by constant twiddling with the database?