My Cow can't switch their role to handle curses-- is there any alternative way to get rid of them?
Certain cursed gear force changes someone to another class - and prevents changing to other classes. Fulfilling the requirements to uncurse that gear should let you change classes.
In general, cursed classes need to be raised to rank 3 (Veteran) to uncurse a lot of their class specific gear. I think the Weapon slot especially forces or prevents changing classes. (As each class has different weapons)
Your Cow probably has something still a "Cow" cursed weapon forcing them to stay that class.
There's only the one way to handle curses at present - fulfilling the uncurse requirement.