For me im still inclined to either integrating the present sweeps n scoops in stick with quarter/ circles or LB RB combo and get Leave to LB certainly fits for me, Its definitely a low priority sub niche one of now with AI and fielding issues, but the levels of immersion and depth that a good functioning leave will brings to test gameplay is certainly worth looking in to atleast for next iteration if not for this one.
The next edition won't add more buttons to the controller though. There's very little room to make adjustments in the assignments without making radical changes to a broadly good batting system. Additive things like making the triggers effective when using the advance/special shot buttons - to allow for slog sweeps, advancing shots along the ground, etc. would be the main area I would want to see change.
The basic problem with assigning sweep to a LB+RB combo is that if you pressed RB first, you'd dance down the wicket. And I'd again make the point, a sweep is an absolutely primary cricketing shot.
However the flipside of that is also true - given that you aren't locked into leaving the ball until just before it goes past the bat, you could assign LB+RB to advancing shots, and make RB leave, when combined with RS movement at the right time (because as discussed earlier, you still need that timing element).
just tried it in the nets doesn't seem to work for me though.
I had a bit more luck when I tried it. But just shows that it needs some tweaks to where those shots go. It's still quite different to the forward push that pushing up on the stick achieves.