Here we have the infamous Dai Li of Ba Sing Se

The Dai Li Agents are all Crystal Ponies (or, in this case, the Lusterless Crystal Ponies)
Long Feng is Cheerilee
Joo Dee is Bon Bon

Casting Long Feng was probably one of the more difficult casting choices since we’d originally wanted the Flim Flam brothers to play him jointly, but then decided that no Pegasi or Unicorns could earth bend which threw them out as candidates. We eventually cast Cheerilee in this capacity because A) Dan really likes her and didn’t want to leave her out of his narrative and B) we figured her desire to make ponies happy (by learning, in the show) could easily be twisted in this world to wanting ponies to be happy by ignoring the bad in the world.

Bon Bon as Joo Dee was a given because of the fandom joke that there are many Bon Bons (as each of her speaking roles has been voiced by a different person.) And with two different Joo Dees making an appearance, it just had to be done.