Two points.
The law expects a pastor to “take possession” of the parish and this is appropriately done in a liturgical celebration. But, such an event is not required. I wonder if it isn’t too lightly ignored, however, or isn’t even considered…or has been forgotten.
"Can. 527 §1. The person who has been promoted to carry out the pastoral care of a parish obtains this care and is bound to exercise it from the moment of taking possession.
§2. The local ordinary or a priest delegated by him places the pastor in possession; he is to observe the method accepted by particular law or legitimate custom. The same ordinary, however, can dispense from that method for a just cause; in this case, the notification of the dispensation to the parish replaces the taking of possession.
§3. The local ordinary is to prescribe the time within which possession of a parish must be taken. When this has elapsed without action, he can declare the parish vacant unless there was a just impediment."
Second, the law allows pastors to be appointed for a specific term but prefers pastors to be appointed with no predetermined “term limits.”
“Can. 522 A pastor must possess stability and therefore is to be appointed for an indefinite period of time. The diocesan bishop can appoint him only for a specific period if the conference of bishops has permitted this by a decree.”
Dan