I'm the first to resist American incursions into the Queen's English
as she taught it to Australia, but I'm more than happy to see this one
become part of our lexicon! As I pointed out, it's necessary to learn
the fraction type nomenclature if you're going to learn LilyPond. One
possible compromise would be to leave it as is (or was) but provide a
link to this page in the glossary:
http://lilypond.org/doc/v2.11/Documentation/user/music-glossary/
Duration-names-notes-and-rests.html#Duration-names-notes-and-rests