To be honest, I just don't like the idea of giving merits on local boards. I am sorry if I sound like a bad guy but I would say that local boards feel the national pride and duty to help each-other to rank up and give merits to their compatriots.
That's definitely a contrarian viewpoint, and though I certainly understand your point about nationalistic favoritism, the fact is that this forum is a global one and not everyone here speaks English well, if at all. And though I don't know this for sure, I think most existing merit sources cover one or two languages at most, and English is usually one of them.
Where does that leave members of a board like the Polish one, the members of which might not have a lot of merits to spread around? Well, it leads to the situation that OP described, a board that has (presumably) a lot of good posts that are going unmerited. Personally I've always supported local board merit sources, and I think each one should have at least one source on the lookout for good posts. As far as the national pride thing goes....these are only merits we're talking about, languages a minority of members speak, and if it were my country that had a local board with abysmal merit distribution I'd be asking Theymos to appoint someone to be a merit source for my community.
Shoot, I'd help out the Polish board
if I spoke Polish, but I don't. Therein lies the problem, no?