The regeneration ability is troublesome, and it needs work on its wording.
The troublesome part is that you're talking about a creature who, assuming 10 Hps per level, can be at full health after only resting for one minute per character level.
The wording part is odd because it's not clear if taking fire or acid damage stops your regeneration for just one round or until you take a short or long rest. If the damage only halts your regeneration for a single round, then the refreshing on a short or long rest part of the mechanic (as well as no action being mentioned to use it) is confusing me.
In one of my settings I have a half-troll race who regenerates by being able to spend a bonus action to use its HDs in combat.That kind of regeneration accelerates healing to when it's needed, but it doesn't alter the amount of healing available to the character during the adventuring day.