Complex sentence: Modern scholarship, however, has cast doubts on the actual quality of Jerome's Hebrew knowledge; the Greek Hexapla is now considered as still the main source also for Jerome's "iuxta Hebraeos" translation of the Old Testament.
Split into simpler sentences: Modern scholarship, however, has cast doubts on the actual quality of Jerome's Hebrew knowledge. Many modern scholars believe that the Greek Hexapla is the main source for Jerome's "iuxta Hebraeos" translation of the Old Testament.