the trainer may be doing this so that when you make armies huge they don't revert back to a hard-coded maximum size..
Because the game devs re-wrote the entire game engine for about the 8th time now in update #41 and it's very time consuming to have to start over with the trainer from scratch whenever they feel like doing this. So, we made the options we had time for which are the easiest to update when the game inevitably updates for the 42nd time. The troop options are the hardest to work out and takes a lot of time only to have it wiped out with the next game patch.
is custom nation points even an option we have?
the custom trainer ability lets you modify the values for each option.