I went looking for something like SuperEdi because NoteTab doesn't handle macrons. SuperEdi handles macrons, but can't read the .aff file as anything but cokebottles, though NoteTab reads it as plain text.
I have actually now been using SuperEDI for this purpose for a month or so. I don't recall exactly what I did to get it to work, except that I believe I changed the font specification.
.aff files are affix files for use with Hunspell, and presumably other spellcheck systems.
Can't edit .aff files