Hello :3 I commented on the slow motion Sakuya video but i guess you missed it XD
It's a little nitpicky, but I'd like to point out that a proper curtsy is usually done with the right foot behind the left :3
And by that, I mean the right foot should cross behind instead of just extending it back XD
In the taunts and sfx vid, the Sakuya on the right side, (the blue one), really does look like she's just bending down.
Because the taunt goes so fast, may I also suggest emphasizing the arms a little? :3 It looks like she is just stretching her skirt XD
When she bends down, raise the arms and shoulders very slightly, and then lower them on the way up.
The way you animated it, it seems like you simply returned the arms to her default, crossed arms position when the taunt ends, so maybe you should lower them back down, and complete the curtsy before returning to the default pose.

Hope this helps
