Quick actions are not swift actions in D&D and represent a greater expenditure of effort, in NWN this means there's a bare minimum of animation tied to it usually because it gives the convenience of the timed delay expected, and this also means it'll be prone to hardcoded quirks of animation locks, character-initiated nterrupts with AoOs, and consumption on a failed activation.
The functions of NWN that cause it are beyond developer control. There are some scripting alternatives that can be applied to the feat that have their own drawbacks, but I think the only reasonable one is using a delayed swift action that reduces movement speed considerably while the "dance" is performed.
Though then you can't cancel the shrouded dance to make a hastier retreat if it was mistimed from a distance due to approaching enemies. Being able to cancel it after casting might be situationally useful, but the situations are extremely limited and subjective. May require a poll between community or within the developer team to decide if that's a route they'd want to take with the feat, if that developer decision hasn't already been evaluated & decided on.
What could be fixed immediately I think is when Shrouded Dance is consumed. By default using abilities get used up when the activation has gone to a certain point, but the counter drain can probably be shifted to a successful completion instead. That particular aspect of NWscript i've not looked at personally though so I could easily be wrong there.
