One wonders here if this name shouldn’t be Corianton, the same as the name of one of Alma’s sons. The only difference is the final n/r, and we have already seen that Oliver Cowdery frequently mixed up these two letters, especially at the end of a word (see, for instance, under Mosiah 2:15–16 for a case involving clean versus clear, also two cases involving even versus ever).
However, in reviewing all the manuscript examples for Corianton and Coriantor, we find no confusion. In the book of Alma we have a clear n at the end of each instance of Corianton, and in the book of Ether there is a clear r at the end of each instance of Coriantor.
As far as other Book of Mormon names and words are concerned, the text has examples ending in on and or:
Although more examples end in on, there are names ending in or. Thus we apparently have two very similar, but different, names, Corianton versus Coriantor. One example of a mix-up in the text between n and r (in this instance, a case of metathesis) is found in the name Comron, which the 1830 typesetter changed to Comnor (twice in Ether 14:28).
This difference between the Nephite name Corianton and the Jaredite name Coriantor supports the earlier decision to keep distinct the Nephite name Morionton from the Jaredite name Morianton (see the discussion under Alma 50:25). Also note the systematic distinction between the Jaredite name Corihor and the Nephite name Korihor.
Summary: Accept the difference in the final letter for the name Corianton (found in Alma) and the name Coriantor (found in Ether).