I went to four funerals between the age of 12 and 16, all for much loved aunts or uncles. I only remember crying at one and that was because my aunt broke down very suddenly and I had an overwhelming feeling of sympathy for her.
My mum died earlier this year and, whilst I cried on the day she died and the day before the funeral, I didn't cry at the funeral. She had dementia, had been ill with a chest infection that turned to pneumonia and had been in hospital for 6 weeks by the time she died. I think I was probably worn down by it all to be honest, plus, because we had entered lockdown by the time we got her funeral organised, it took a month to have the cremation after she died.
But that doesn't mean I didn't care for any of my aunts, uncles or my mum. I saw a programme on the TV the other day that featured a song that my aunt (who's now been dead over 40 years) used to love and I welled up. We celebrated DH birthday recently - it falls very close to mum's - and that was a wrench as we're normally doing something for her a few days later.
And, whether she has autistic traits or not, does it really matter? If lack of empathy is an autistic trait (I only know one child with autism and he is very empathetic so I can't comment), then that's the way she is.
My sister was in bits on the phone for weeks after mum died and bawled her heart out at the funeral. But that's not me. I grieve by remembering the happy side of the person's life more than I think about them being gone (maybe that's a defence mechanism to save me feeling too bad??)
The point is my sister wasn't wrong to be crying all the time and I wasn't wrong to not. We're different people with different ways of thinking, so we're bound to grieve in a different way.
I am sorry for your loss but don't worry about your daughter. Just talk to her now and then about her aunt, in general terms, if she wants to.