Speaking of my childhood, that time my favorite cartoons were not Soviet. Though that time we were not shown any "western" ones, there were a lot of cartoons made in countries of the former Soviet block. Czech cartoon series about the mole, Hungarian full-length cartoon "Saffi", Romanian full-length cartoon about mice playing musketeers - they were may favorites. As for Soviet cartoons I liked to watch in my childhood I can name only "Nu pogodi". (Btw back in the Soviet Union they made a lot of cartoons with puppets, I disliked him very much).
But when I grew up I found out that there were a lot of adult cartoons in the Soviet Union. My favorite of them is "The contact" (Контакт) https://www.youtube.com/watch?v=citTQLOWiVo
I also like this one https://www.youtube.com/watch?v=fBucJGYorQ0 'll give you the star" (Дарю тебе звезду)
and this one https://www.youtube.com/watch?v=2MVuSvWPf1E "Very blue beard" (Очень синяя борода)
and the Ukrainian folk cartoon you have given a link to is very funny and I can say I like it too.
And there is a Russian made cartoon series that I like very much, its name is Smeshariki (some of its episodes were translated to English and are known as Kikoriki or GoGoRiki). Btw since you have seen "Hedgehog in the Fog" I'd like to recommend you to watch an episode of Kikoriki named "Hedgehog in the Nebula" (Ёжик в туманности), in Russian the world Fog (Туман) and Nebula (Туманность) sound very similar and "Hedgehog in the Nebula" is a parody to "Hedgehog in the Fog".