@pom you very well know me. I choose shows very carefully and at this point like you Maya holds my interest exactly for the reasons specified by you and jenny is perfect in each frame.
No we are not yet sure whether her father sexually abused her, though evidence of extreme physical abuse ( I mean continuous slapping, maybe burning hands, legs etc..that kind of violence) was shown.
Something happened on Maya's 9th b'day which turned her world upside down is what we understand though we dont know what exactly happened
Some hints includes Maya or her mom has gone to police for something , her father became angry locked her up in a room
Then it seems Maya has some psychological disorder which is not properly treated and her father calls her mad now and then. Dont know it has deeply affected her.
Maya's father domestically abuses her mother extracts money and lives with his mistress
Her mother is a doormat and to some extend she is more responsible for Maya's condition than her father
So Maya's past many things are unsaid at this point and I feel to keep the thriller element of the story that is necessary