I'm going to tell my daughter that her animation is not that good
If she worked hard on her animation then telling her this could be hurtful.
I want her to be great so I need to be honest.
It is good to be honest with someone about their art if they want to get batter. You should be kind about it and not be overly rejecting and hurt their feelings.
It's my kid, I can tell her whatever I want.
Because they're your kid you should try to give them constructive criticism that isn't overly harsh. The world is a harsh enough place that won't coddle your child. It's better to build them up and prepare them than to just be overly blunt.