The bot will occasionally attempt to cast curses from slightly out of range. It wont move or take any actions unless the player moves the character. Doesn't happen often.
The Exile CR does have issues with certain skills. Trying to make a generic CR that handles most skills has proved to be more tricky than expected. In the beta version of the bot, they were commented out as a result.
If you make your own CR, then curses will work fine as long as you check to make sure the mob is cursable, and you have the target in line of sight first.
Please see this post for how you can do that in your own CRs if the Exile isn't proving to be good enough for you right now.
I disabled Curses temporarily until I can figure out a better logic system for them. (I'll likely be changing it to blanket-curse and rare+ mobs, but I haven't gotten around to it.)