>>11864612FF2 translation was 90% done and planned for release; while they were talking about releasing FF3 on NES down the line as well. Then in a matter of months they did a 180 on that.
I have a schizo theory that Nintendo of US prevented the release of FF2 (and by extension, 3) on NES out of spite for Square not going through them for the publishing anymore (FF1 but also Rad Racer and 3-D World Runner were published by Nintendo in the US and were all best sellers, then Square sat up shop in the US) and because they were afraid they could out perform them.
For the SNES they needed all the chips they could get to make customers buy a new console (the SFC had a very slow first year in the Japan so the US branch had an example not to follow) they wouldn't have bothered FF4's release.