On the other hand, "autor" and "autorka" are normal forms; same for "lekarz" and "lekarka", "nauczyciel" and "nauczycielka". These seem to be equivalent to the shorter forms you list. I'm not sure how to translate your longer forms, "nauczycielniczka"? There's no such word.
Interesting to see that different languages can have perfectly opposite grammar rules, even if the words are similar and the grammar also shares some similarities in other areas :)
Nope, no equivalent to "sibling" at all, not even plural. If you want to say "siblings", you say "братья и сёстры".
edit: "родня" might be kinda like "rodzeństwo", but it's not just siblings, it's relatives in general.
> I'm not sure how to translate your longer forms, "nauczycielniczka"? There's no such word.
"Учительница" (or short slang form "училка") is the correct feminine form found in dictionaries. "Учителька" is the cringy one coined by feminists. They both mean "female teacher", but apparently the correct one is somehow worse or not modern enough? I don't know.
What about дитя? Isn't that a neuter in Russian? I know the equivalent "dítě" is a neuter in Czech. (For obvious reasons this is why the neuter is not being used in Czech either for referring to adult people -- it's completely infantilizing.)
But we do have another similar phenomenon going on. Feminitives. It's when some people assign the female gender to words that don't have a female form, or that do have one but it's not cringy enough. So автор becomes авторка, врач becomes врачка (instead of врачиха), учитель becomes учителька (instead of учительница), and so on.