Complex sentence: Modern scholars have demonstrated that Assemani's attribution to Dionysius was mistaken, and the anonymous author of the text quoted by Assemani is now referred to as Pseudo-Dionysius of Tel Mahre.
Split into simpler sentences: Modern scholars have demonstrated that Assemani's attribution to Dionysius was mistaken. Its anonymous author is sometimes referred to as Pseudo-Dionysius of Tel Mahre.