1. If you hit a difficult consonant, replace it with d.
2. If you hit a difficult vowel, replace it with u.
3. All syllables must end in a vowel. If the English syllable ends in a consonant, either leave it off or add a vowel.
Thusly:
all done --> adu
down --> dow
dog --> doDEE!!!
diaper --> didu
water --> dadu
shoes --> du
toes --> doe
Translating the other way is . . . tricky.