I believe Plasma Beam is overpowered on purpose, so I don't want to complain about how overpowered it is, instead I'd rather point out that other schools don't have spells that are similarly powerful, and they should.
I have not tried 4 of the spells added by the update because their usage never comes in my usage of psi, so I can assume that Cryogenic Barrier is only an aggressive, waterborne version of Force Field that can encase enemies, Psychosomatic Predation is only good if you use weapons instead of relying on psi for damage (maybe even being very useful for TC Knife builds), Motor-Cognitive Transferrence is mainly for crippling the combat abilities of a target (I assume the bonuses are not significant enough to decently improve a wielder's weapon stats, unless the wielder has 0 combat skills and enough TC to steal a huge amount of combat skills), Telekinetic Grounding could be decent for crossbow users and for those with absolutely zero skills in throwing, and Psychokinetic Chain is weak due to the damage limit, but may be more useful than I believe due to it working with Electrokinesis and sources of multiple damage (I believe you can throw a grenade into a group of linked enemies and the damage from shrapnels will be shared)
If damaging psi abilities will happen to be far stronger without needing critical damage bonuses to be viable then the Waterways update will eventually be justified (please rework the innervation system the slots are a shit mechanic), but why they weren't shipped with the Waterways update is unknown to me.