He was one of the people in attendance at the Synod of Birr, which probably means he became a bishop at one point. The Synod of Birr was a meeting of 697 of a number of bishops, abbots, and nobleman from Ireland, Scotland, and Pictland which promulgated the Cáin Adomnáin (named after Admonán, the ninth abbot of Iona), or Lex Innocentium, which guaranteed that a distinction should be made between warriors and non-warriors in battle, and established a generally agreed-upon law among the nations involved for how to handle soldiers killing or raping women, or vandalizing church property. The content was not in every respect new; some of it was traditional Gaelic custom, and some of it was what Christian preachers had been exhorting for years. And it does not seem to have actually been enforced at any point -- but it did get all the nations in the area to agree explicitly on at least the principles, and it made respect for such principles at least a matter of honor for them. Honor is a weak enforcer of explicit norms -- but it is a steady pressure in their favor.
Egbert became heavily involved in the Easter controversy, and was a major figure in convincing various powers in the area to accept the Roman dating of Easter. Because of this the Venerable Bede speaks of him very highly. St. Beda's comments on death:
The monks of Hii, at the teaching of Egbert, adopted the catholic manner of conversation, under Abbot Dunchad, about eighty years after they had sent Bishop Aidan to preach to the English nation. The man of God, Egbert, remained thirteen years in the aforesaid island, which he had thus consecrated to Christ, as it were, by a new ray of the grace of fellowship and peace in the Church; and in the year of our Lord 729, in which Easter was celebrated on the 24th of April, when he had celebrated the solemnity of the Mass, in memory of the Resurrection of our Lord, that same day he departed to the Lord and thus finished, or rather never ceases endlessly to celebrate, with our Lord, and the Apostles, and the other citizens of heaven, the joy of that greatest festival, which he had begun with the brethren, whom he had converted to the grace of unity. And it was a wonderful dispensation of the Divine Providence, that the venerable man passed from this world to the Father, not only at Easter, but also when Easter was celebrated on that day, on which it had never been wont to be celebrated in those parts. The brethren rejoiced in the sure and catholic knowledge of the time of Easter, and were glad in that their father, by whom they had been brought into the right way, passing hence to the Lord should plead for them. He also gave thanks that he had so long continued in the flesh, till he saw his hearers accept and keep with him as Easter that day which they had ever before avoided. Thus the most reverend father being assured of their amendment, rejoiced to see the day of the Lord, and he saw it and was glad.