ayy! glad to hear you’re diggin in 
loop sync across banks will match the current loop points of bank to the loop points of another. which one depends on the gesture.
x x x -: sync to previous bank
- x x x: sync to next bank
let’s say you have these loop points:
a |------|------------------
b -----------|---|----------
c ---------|-----------|----
performing x x x - in bank b will sync loop b’s current points to bank a (since a is “previous” to b):
a |------|------------------
b |------|------------------
c ---------|-----------|----
performing - x x x in bank b will sync loop b’s current loop points to bank c (since c is “next” after b:
a |------|------------------
b ---------|-----------|----
c ---------|-----------|----
the prev/next logic works out as:
a: prev = c, next = b
b: prev = a, next = c
c: prev = b, next = a
hope this helps! i’m really glad you brought this up because I just successfully added variable clip length import (up to 32 seconds) and this needs looked at for the upcoming release 