How do those leagues work if the higher league has an imbalanced proportion of regions? i.e. Region A has 3 teams relegated from the higher league, but they’re only promoting 1. Is their regional league just bigger the next season?

I think in this specific scenario (vanarama national), it could do with more promotion spots, and league two with more relegation. The gap between the top vnl sides and league 2 isnt that drastic, but only two teams go up and two down. There should at least be two automatic promotion spots plus a playoffs in my opinion.