If I were in charge - that's a scary thought, isn't it - I would probably appoint a couple of moderators to each of those underserved boards. For example nutildah and DireWolfM14 for P&S, LoyceV with o_e_l_e_o for BD/Press, dkbit98 and Lucius for Croatian boards, mainly to punish them all for complaining so much

but also to give a bit of a proactive push to clean those boards instead of waiting for reports, which could be a good deterrent without banning. And I'd hope that having two mods work out some sort of agreement between them could help with the inevitable bias accusations and moderation complaints. If they start slacking a year or two from now, pick someone else from active users.