There is a lot you're claiming here that still doesn't match with either physics or neurology. I'm not trying to berate you, but just point out the fallacies.
"doing a specific technique in the water will make that technique slower because you get used to throwing it slower".
According to who? Not according to weight resistance training of any type in exercise science that I'm aware of. Training against resistance never makes you slower. In fact, one look at surfers should show you training in water makes them not only stronger, but faster than most "martial arts" types.
", if you practice a front kick in the water you will be throwing it at a slower speed because of water resistance and as such your brain will become programmed to throw it at that slower speed even when you're not throwing"
It will be at a marginally slower speed because of resistance in the water, but that has no bearing on when you're out of the water. Not to mention, anybody training front kicks in the water, are probably also training them outside of it.
What's your source for this "brain programming" thing? That just sounds like more of an unsupported opinion. I'd like to see some actual evidence.
Like I've said a few times, the whole "training with resistance/weights makes you slower" trope, which also conflicts with mainstream exercise science, appears to come from a lot of literally weak martial artists who think they're fast.