Concerning pre-industrial tech NPRs, you said they'd have ground forces. What manner of ground forces would they have? Muskets? Swords? Does it depend on where in some hidden tech tree they are?
Now that you are also planning industrial era NPRs as well, does that also imply that pre-industrial NPRs can become industrial era?
Pre-Ind have the same ground forces they have in v2.5.1, with armour and weapon strength 1. Pre-industrial cannot advance to industrial. They are centuries apart. It's like Rome, or 16th Century Spain, advancing to WW2 Germany.
Pre-industrial and Industrial are fixed tech civilizations - more like special events than serious opponents, although the industrial NPRs could play an interesting role if they end up between two high tech empires.