Yeah you assume correctly, they must be summoned in short range, though that works well if you engage in a CQC fight. Moving on, and same as your other training I'm pretty sure you can use the sword tech without Samehada, since it mentions being used by shark signers and they can't have that sword.Noted!
Shark Teeth is a nice technique that reminds me a bit of some Kaguya clan applications as it generates sharp objects that can be sent towards the opponent. It allows for the teeth to be shot at a range after being summoned or even be used to crash from the opponent from above. I'm assuming it's summoning from above must occur in short range due to the initial wording of the technique, a minor setback but nothing that major I guess.
I guess I'll have to fight on ponds mostly to use a few of the next ones or create a custom to alleviate some of the water restrictions. Breakthrough is basically a water projectile that's restricted to short range w/o hand seals, while Shark Bomb is the same but at a distance though with handseals and w/o the need of a water source.