Complex sentence: He was seen as guardian of the dead, all the more a crucial role given the effect of plague, especially given the outbreaks there between 1441--42, just before Rolin's foundation of the hospital.
Split into simpler sentences: He was seen as guardian of the dead, all the more a crucial role given the disasters wrought by the plague in the region. There was a sever outbreak there between 1441--42, just before Rolin's foundation of the hospital.