I didn't noticed for girls animations. But that's annoying. I know it's only cosmetics and it don't affect the gameplay but html5 version should bring better qualitiy, not remove it
I don't know it's a cache issue. I cleared my cache some times since version change and it didn't fixed this.
Sorry for you. I would recommend defensive girls and team for this boss. It have a damn lot of HP but don't hit that hard with normal attacks. The main problem is it's special attack with 100% chance turn 3. It kill all the offensive crit teams.
I use my counter Crit (aka Pink Miko alone) and my Saffron+Kerria team to deal the main damages and I finish with my Crit team. Maybe. If there is still something to kill.