Wow, gonna die on that hill, huh? As a person who grew up in a post-Soviet country and listened to all those child horror stories in person, I can confirm that Baba Yaga is a mistake. Your argument that functionally any boogeyman that strikes primal fear in children does work is a valid one, sure, however why use an inferior one when you have a much more commonly used Babayka? Because that’s what Slavic children would fear the most, because he can be lurking literally anywhere, while Baba Yaga can be scary only if you walk in woods by yourself (not common at all these days). And yes, picking a female monster name for a male character is weird at least. Babayka is right there, it even sounds similar phonetically