Yeah, I woke up today excited to play xerath as I expected his Q to be fixed of that issue... His ult, while fixed, was not much of a problem for me, however, his Q is the same as if you try to redirect the line too quickly and release it won't pick up the last mouse movement and end up way off.
I would assume there to be at least one game played by riot to ensure these bugs fixed. Since it happens every time, it wouldn't be hard to know that its still an issue. Guess I'll have to wait another 2 weeks or so for 5.9 T_T