appointing pastors for a term, rather than permanently, is *not* the norm for the RCC.
Rather, the norm is permanent appointment, with a provision allowing national bodies of bishops to set a term, an option which the US bishops have taken.
I've never heard of a fixed term for an eastern parish but that doesn't mean that it doesn't exist anywhere . . .
A few years ago, a Ukrainian Catholic priest retired at just shy of 50 years in the same parish . . .
Chatting with my own priest, he noted that as a pastor, rather than administrator, he has some level of right to not be moved without cause. (Pittsburgh Metropolia).