I've eaten pierogi in Germany, Poland, Ukraine, and Russia, and the diversity and breadth of the dish makes them totally different than what you can find in Romania. I would say that colțunași are a subset of pierogi, since they're only filled with fresh cottage cheese filling and served only with sourcream (smântână). Also, I've encountered them only in the northern part of the country and nowhere else. So, I wouldn't say that we eat the same dish in Romania. Please let me know if you have found them in other parts of the country.

We have them in neighboring Slovakia too (not surprising), filling is mostly some potato+cheese paste (but you can end up with sweet ones with ie plums in some households).

The dough is pretty much tasteless, so depends what you fill into it and what you pour on it. Overall nothing comparable to say French fine cuisine but its a bit of our history since historically peasants ate these kind of things and meat was only for special occasions.

There is hardly any grain-cultivating population in the world that doesn’t have dumplings of some sort. Interestingly, however, the Romanian term colțunași is from Italian by way of Modern Greek, so it cannot be more than a few centuries old in Romanian. One therefore wonders what the earlier Romanian term for dumplings was, or whether dumplings were commonly eaten at all when the Vlach economy was still centered around transhumance.