The Ki values are very much correct, it is an exact match on a Spell Slot to Ki point buy rate of exchange. They do push out other Monk Ki abilities, but as a full fighting class getting those spells on a short rest basis...that is worth something, and the math is right. If the playstyle matches the design, it works fine. The problem is that unlike most other options in the game other than the Beastmaster, the intended playstyle is mismatched with player desires.
Here's where you lose me. What are the player desires in this situation? The desire to be a monk and use their subclass abilities? Because that is what we are talking about. This isn't based on something like "the player's want to use this monk as a tank" or something else, the literal desire we are talking about is the desire to play the subclass and use the abilities.
Maybe you are right that the math works
in theory, but
in practice it doesn't actually work.
Here, let's just show this at a very very very basic level. You get the subclass at level 3. At Level three, monks have 3 ki per short rest. To use an actual ability costs 2 ki.
Fist of Unbroken air is two ki, for a strength save that does 3d10 bludgeoning damage. That sounds very powerful, right? You can do it once per short rest, but that's an average damage of 16.5 damage if the enemy fails the save, and it is the strongest damage for these abilities. Fangs of the Fire Snake has shorter range and 2 ki lets them only deal 1d10 damage, for an example.
What else can you do with 2 ki as a base class monk? You can make 4 unarmed attacks. That is 4d4+12 damage, or an average of 22 damage if they hit.
So, already, very beginning, I can spend 2 ki in a single action, and do less damage than if I spent that ki using non-subclass features. But it gets worse. Fist of Unbroken Air is an action, but it isn't an attack. So... you can't use your bonus action for anything after doing it. It also doesn't work with monk abilities like Ki-Empowered strikes, or Stunning Strike
So, that's 3d10 damage for the entire turn. IF you were using your bonus action with ki for flurry instead, you could still attack with your main weapon, which will likely be a staff for an additional 2d8+6 or 15 damage.
So, 2 ki in one turn for 16.5 or 2 ki over two turns for 37 which is 18.5 per turn.
So, every single target ability (which is three of your six options) is only useful if the monk, one of the fastest classes in the game, can't close into melee range. In terms of pure damage, they are a downgrade of your abilities. But the other two are AOEs, so does that help? Not really, both of them are close range AOEs, and to do better than the damage of just punching the enemies, you need at least three enemies to be next to the monk. Which is a big risk, especially since... that's it. You don't get a second shot. So, in a single turn of a single combat, you blow all of your subclass abilities.
Or, over three turns, you just act as a normal monk. Which is generally getting you better results anyways.