Nah. I don't think Epiphanius knows much about the Ebionites. Let's continue with the methodology of his 'new information' about the Cerinthians.
As you noted the bit that follows the introduction is all from Irenaeus. But then the wild identification of Cerinthus as Paul's opponent is wholly new.
Cerinthus lived in Asia and began his preaching there ... this man is one of the ones who caused the trouble in the apostles’ time, 8 when James wrote the letter to Antioch and said, “We know that certain which went out from us have come unto you and troubled you with words, to whom we gave no such commandment.” 9 (4) He is also one of those who opposed St. Peter because he had gone to St. Cornelius when Cornelius had been vouchsafed a vision of an angel and had sent for Peter. And Peter was dubious and saw the vision of the sheet and the things that were in it, and was told by the Lord to call nothing common or unclean. And so Cerinthus stirred the circumcised multitudes up over Peter on his return to Jerusalem by saying, “He went in to men uncircumcised.” 10 (6) Cerinthus did this before preaching his doctrine in Asia and falling into the deeper pit of his destruction. For, because he was circumcised himself he sought an excuse, through circumcision if you please, for his opposition to the uncircumcised believers.
11 3,1 But because the Lord unfailingly cares for mankind, safeguards the clarity of the truth in the sons of the truth, and has granted the holy apostle Peter to give the refutation of Cerinthus and his party, the stupidity of Cerinthus becomes evident. (2) St. Peter said, “I was in the city of Joppa, and at midday, about the sixth hour, I saw a sheet let down, knit at the four corners, wherein were all manner of four-footed beasts and creeping things. And he said unto me, Slay and eat. And I said, Not so, Lord; for nothing common or unclean hath at any time entered into my mouth. But the voice answered me again from heaven, What God hath cleansed, that call not thou common. And, behold, immediately there were two men already come unto the house, and the Spirit said unto me, Go with them, nothing doubting.” 12
3,3 And then he explained how this had been said to him as a parable and how he had been doubtful at the time, till the Lord showed him plainly the things he was teaching him through the words and images. (4) For the instant he opened his mouth when he had come to Caesarea, the Holy Spirit fell upon Cornelius. And seeing this, Peter said, “Can any man forbid water to these, which have been counted worthy to receive the Holy Ghost as we were at the beginning?” (5) But all this was a mystery and an act of God’s lovingkindness, so that St. Peter and everyone else would realize that the salvation of the gentiles is not of man but of God. God had granted the gift of the Holy Spirit, the vision of the angel, and the acceptance of Cornelius’ prayer, fasting and alms, beforehand, so that the apostles—St. Peter especially, and the other apostles—would deprive no one truly called by God of that with which they had been entrusted.
4.1 But these doings took place then at the instigation of that false apostle Cerinthus. Another time too, he and his friends caused a discord at Jerusalem itself, when Paul arrived with Titus, and Cerinthus said, “He hath brought in men uncircumcised with him”—speaking now of Titus—“and polluted the holy place.” 13 (2) And so Paul says, “But neither Titus, who was with me, being a Greek, was compelled to be circumcised. Butbecause of the false brethren, unawares brought in, who came in privily to spy out our liberty which we have in Christ, to whom we gave place by subjection not even temporarily.” 14 And he used to command the uncircumcised, “Be not circumcised. For if ye be circumcised, Christ shall profit you nothing.” 15 (3) Circumcision was a temporary expedient until the greater circumcision arrived, that is, the laver of regeneration—as is plain to everyone, and is shown more clearly by the things the apostles said, especially the holy apostle Paul. For he insists, “To them we gave place by subjection, not even temporarily.” 16
4,4 But to anyone who is willing to observe what the apostles went through at that time, it is amazing how the things a spirit of imposture
inspired this faction to do betray the character of those who caused the commotion among the apostles with their heresies. (5) For, as I have said,
no slight disturbance arose then, after they had rebelled, become false apostles, < and > sent other false apostles—first to Antioch, as I have said already, and to other places—to say, “Except ye be circumcised and keep the Law of Moses, ye cannot be saved.” 17 (6) And these are the ones the apostle Paul calls “false apostles, deceitful workers, disguising themselves as apostles of Christ.” 18
Clearly this is not an actual 'historical tradition' regarding a heretic named Cerinthus but rather a massive re-interpretation of literary evidence to include and identify Cerinthus as an ancient figure. Clearly no one knows anything about Cerinthus beyond what Irenaeus wrote.