Random thoughts.
1. Apparently "dominate" is a defined keyword.
2. I assume that "charm" is also a defined keyword, because otherwise there's no reason for the charmed target to stay near the succubus. Instead, the player of that character would have it immediately leave to fight a different enemy, preferably by a path that leads right past the party fighter or paladin, where the succubus would fear to follow. I don't know how I'd fix this. I've never liked charm effects, because its always been tough for me to reason how the charmed character would see one enemy as his ally, but not the enemy's allies as his allies. This partially fixes the problem by making the effects of charm precisely defined, but I still need a little more precision. Maybe its off camera.
3. There must be a default flight maneuverability, because the war devil is defined as "clumsy" while the succubus has no defined maneuverability.
4. Part of the purpose of per encounter abilities, per day abilities, and for monsters, recharge abilities, is just to create variety. I have, for a long time, loathed the way that D&D encourages purely spamming attacks. I've wanted fighters who fight with a sword in one hand, and the occasional left hook, or something, anything, to create more variety. So... yeah, its not realistic that the war devil "can't" use his trident every round. But this is a "the rules are not physics" issue. The recharge effect allows two things. First, it allows the designers to give the war devil an above average power level trident attack, because they know he can't use it every round. So it satisfies a balance need. Second, it makes the war devil more cinematic. Instead of a 3e style monster that attacks with his trident every round, now he spears one character with a trident, claws another, swings his trident around to attack a third, etc. It keeps things active and dynamic. Its not that he CANNOT use his trident every round. Its that it was unrealistic that he USED to use his trident every round, and now, thanks to an unrealistic recharge mechanic, a more realistic outcome has been achieved.
5. The Level 21 Encounter may seem like it has a lot of monsters, but take a look. There's 12 level 21 minions (counts as 3 pcs), 1 level 22 leader (counts as ?? just over 1 pc?), 1 level 20 soldier (counts as ?? just below 1 pc), and 2 level 17 controllers. The level 17 monsters seem to be the only real surplus, and they are four levels behind the level of the encounter. That might make it a tough fight, but perhaps not. No way to tell at this level.
Maybe minions become less useful as the players go up in level, and gain more area of effect attacks?