Complex sentence: It is unclear why Eriugena made a new translation so soon after Hilduin's--it has often been suggested that Hilduin's translation was deficient, and this is a possibility, but it was a serviceable translation.
Split into simpler sentences: It is unclear why Eriugena made a new translation so soon after Hilduin's. It has often been suggested that Hilduin's translation was deficient; though this is a possibility, it was a serviceable translation.