are there any trigger mods that are illegal?
Yeah, anything that changes the amount of raw input the game processes is banned. Basically, this means disjointing the correlation between player input and action taking, such as holding R and shield spamming on andoff with perfect frame data (turbo). As for L and R, I think removing the full pressure sensitivity or its effects is also a nope, since soft shielding will always come before hard shield regularly. If you were able to skip that stage, perfect shielding would be much more commonlace and thus rely less on skill. It would have drawbacks of course, but it's still kinda broken.
TLDR If your character in-game matches your inputs, you're probably good. Don't try to be too gray area-ish with this, TOs will get pissy (and rightly so, it adds to their already immense workload).