"There are some other examples of female characters playing a big part in myth (most myths about Freyja, Idhunna, to some degree Athena, and maybe some others)" - Sure, but regarding a divine trinity having a daughter it's just the one case: do you have any opinion on whether that might be part of the Etruscans awarding women higher status than other societies of the time? (Seems to me that a society having an important "fertility goddess" doesn't mean it does particularly well regarding human women.)

"I think a lot of Indo-European myth is actually weirdly supportive of the idea of nuance in both what goes right and what goes wrong." - I certainly tend to think the same, but a bit of me wonders: "Compared to what?", as the only non-Indo-European mythologies I consider myself significantly above rank ignorance regarding are the Abrahamic ones.