Ho, I forgot about this one. ju'e is part of the language, not experimental;
if it is not in the cmavo list, that is an error in the cmavo list. Bob LeChevalier
speaks of ju'e
as "adopted", and says that this includes adding a line to the cmavo list.
Since there is no such line, I suppose the currently posted cmavo list
is out of date here.
It appears that it is mentioned in the cmavo list after all, but nowhere in The Book.
There's a file called "cmavo" and one called "CMAVO". The latter is the new list and contains ju'e.