He appeared is literally “he was seen,” a verb form often used in Greek when speaking of supernatural appearances. In some languages it is possible to render this verb as “let himself be seen” or “he showed himself to.”

Cephas: if translators have used “Peter” throughout 1 Corinthians (Good News Bible), they should use that name here also (see comments on 1.12).

To the twelve: in some languages, or for some groups of readers, it may be necessary to make it appear that the twelve were the original apostles. However, since Paul mentions in verse 7 a group of apostles that was probably larger than twelve, it seems best in translation to omit Good News Bible‘s “all” in the present verse.

Quoted with permission from Ellingworth, Paul and Hatton, Howard A. A Handbook on Paul’s First Letter to the Corinthians, 2nd edition. (UBS Handbook Series). New York: UBS, 1985/1994. For this and other handbooks for translators see here .