I don't know if I trust St Epiphanius. He believed in the anthropomorphic heresy (that God has a physical body)
That’s actually inaccurate. What you are thinking of is St. Epiphanius criticism of the Audians, a group of Quartodecimian heretics, whose errors also included anthropomorphism in the form of a literal interpretation of Adam being created in the Image of God. The position of St. Epiphanius was that this view was in error, and that the nature of how humanity was created in the image of God was a mystery.
and sided with Pope Theophilus of Alexandria in condemning and deposing St John Chrysostom in the Synod of the Oak.
This is also inaccurate. While en route to Constantinople, St. Epiphanius realized he was being used by Pope Theophilus, and that allegation against St. John Chrysostom - that he was an Origenist - was bogus, and so St. Epiphanius turned around and began the journey back to Cyprus. Unfortunately, his health was poor, and he was 80 years old, so he died en route to Salamis, but he died with a clean conscience, because he did not allow himself to be used as a pawn in the sinister designs of Pope Theophilus. Indeed, one could say that he died to prevent that happening (since he was doubtless aware of his poor health and the high risk of perishing during the arduous voyage across the Eastern Mediterranean back to Salamis on Cyprus).
The reason why he set out in the first place was that he was lied to - it was falsely claimed that St. John Chrysostom had become an Origenist, and St. Epiphanius, who, like St. Jerome, was of the view that Origen was largely responsible for the Arian heresy, could not tolerate the thought of an Origenist serving as Patriarch of Constantinople,
Now, I am not saying that St. Epiphanius was devoid of flaws or controversy, but I am extremely confident in the accuracy and reliability of the Panarion, in terms of the conclusions it draws. Also I would note that among Orthodox clergy, St. Epiphanius is actually less controversial than St. Irenaeus of Lyons, because, like many second century fathers, St. Irenaeus was a Chiliast. For this reason Protopresbyter Michael Pomazansky in his classic Orthodox Dogmatic Theology, translated by Fr. Seraphim Rose, felt compelled to warn readers that the works of St. Irenaeus contained doctrinal errors on account of his chiliasm. Now, St. Epiphanius himself did extensively quote the descriptions of heresies provided by St. Irenaeus, to the extent that the Panarion can be thought of as an enlarged version of Books I and II of Against Heresies, but it was not in that work, but rather the dogmatic definition in Books III, IV, and V of Against Heresies where St. Irenaeus was in error.
Of course, the most compelling endorsement of the accurate reportage and Orthodox faith of St. Epiphanius is the use of his epitomes of each of the heresies documented in the Panarion by St. John of Damascus in the heresiological section of his magnum opus, The Fount of Knowledge, alongside newly written material addressing Iconoclasm, Islam, Tritheism, Nestorianism and other heresies which had appeared since the fourth century. The Fount of Knowledge is most famous for the comprehensive treatment of dogmatic theology contained within, An Exact Exposition of the Orthodox Faith.
St. Epiphanius has been fairly frequently accused of heresy, but most commonly iconoclasm, and not by the Orthodox but by iconoclasts seeking to use an ambiguous text that he wrote as “proof” that the early church was Iconoclastic, which we know was not the case, and this accusation has also been debunked.
So in general, my view is that if the work of St. Epiphanius is good enoufh for St. John of Damascus, it is good enough for me.
That being said, I do commemorate your caution. In the specific case of St. Epiphanius however I feel, having read his works heavily and having further written a history of the Origenist controversy which included a biography of him, that his work is very trustworthy. In fact, as ancient historians go, I would say that St. Epiphanius is considerably more reliable than most: I trust him more than Eusebius of Caesarea (who was an Arian sympathizer who I believe was writing his biography of St. Constantine with flattery in mind, with a view to persuading him to change his mind on Arius and Arianism; his earlier Ecclesiastical History on the other hand is more reliable, I think) , and I trust him
considerably more than I trust Flavius Josephus, who strikes me as being totally biased in favor of the Scribes and Pharisees and against the Beta Israel, Samaritans, Sadducees, Essenes, and Hellenic Jews.