> Forms like the imperative (食べろ), volitional (食べよう), provisional (食べれば), potential (食べられる), and causative (食べさせる) aren't cleanly handled either -- they work similarly for godan verbs, but you have to add a different suffix for ichidan verbs.
They are cleanly handled in the final section (“one more thing”) that introduces a notion of disappearing consonant like -[r]u, -[r]eba and so on, and gives a rule for it. This is a perfect inversion of what happens with -(i)masu and friends. The hole in the stem accepts the leading vowel but burns down the leading consonant.
It’s quite elegant.
"Disappearing consonant" doesn't work for the potential form, unless you expand the representation to allow writing -[rar]eru. (Edit: And I think imperative would require like "-[ro](e)".)
Which, like, is clean in the sense that Redux is technically Turing-complete (you can encompass _any_ difference between two strings by saying that one string uses the stuff in brackets and the other string uses the stuff in parentheses), but that doesn't make it a good idea.