Is it possible to use the /facetarget option before casting (if it is pre-cast moving that is causing the problem)?
Is it possible to try to use /macros as well (I have no idea if you can do this with a controller, I am sorry).

All I can say is so far, I have no issue with casting, but I may be unusual (for many reasons ^.^; in that I use a keyboard macro for spells (cure, fire, etc), and only use non-macros for self-targetting spells (shroud of saints, etc.).

I'm sure there are many areas for improvement, and always will be, but perhaps there is some way to work with what is there and still be happy ^.^;

I am hoping in future actions will be more responsive (you press it you KNOW right away if it was accepted or not). Then that will solve many problems including this ^.^