Seems to be a big problem with the slash tiles in 2.5. They're incorrectly offset when facing to the right, and possibly just a bit in the other directions. Right-facing slash is the worst however. Happens in any quest with slash tiles, regardless of whether or not the animation/flip fixes are on or not. To see it, just load up 211test, give the slash ability in init. data, and try it out.
EDIT: I did read that the positions are consistent with GB Zelda (LA). They're not. I tested it, and there's a HUGE difference in position, especially to the right.