Seahorses are meant to be kept only with the most mild mannered of fish. They have a tendency to hitch on any and everything you might imagine in the tank and do not seem to have much regard for previously staked out territory, so keeping them with any fish that are territorial is a no no.
For their size, the dwarf or pygmy angels can be downright feisty and all dwarf angels are territorial. Your Coral Beauty may be well behaved with it’s current tankmates but feisty and territorial fish are not considered seahorse safe or reef safe. Mine is kept an aggressive fish only system with Puffers and an eel. They also like to pick at algae which has a tendency to accumulate on seahorses. The seahorses will not appreciate being picked at by the Coral Beauty. The anemone may make a very expensive snack out of your seahorses. Seahorses should never be kept with an anemone.