Actually, Japanese with Engrish is a great idea and all of my (future) voicebanks
are going to have supplements for engrish. Its not perfect English obviously
but it works, I've done it before.
For this I'm assuming these vowels are pronounced the Japanese way.
Well your list looks pretty good but there's just a few more sounds I'd include.
Your list needs both an English R and a japanese R. I think a few banks do this --
at least mine do -- but I often use "3" to represent the English R. Idk if that's what
most people do though. I usually include a few CV and VCs with the "3" such as
3a and a3 and etc. A few extra sounds with "3" always help too such as
"y3" and "w3" as they're used a lot.
My Japanese/Engrish banks also have pure consonants where they can --
like a solid "k" sound and "j" and pretty much any consonant that can
be stretched out. I made the mistake of forgetting the soft and hard 'th' sounds
and those would really help too.
Lastly I'd add a few more solid standalone vowels such as one for "at" (I call mine "@"),
"fix" ("ih") and book ("6"). Maybe one for "just" ("uh").
It sounds like a lot but that's probably only 20-30 extra sounds tacked on to your list.
You don't have to call them what I do but I just gave my aliases as an example.
For proof that my suggestions really work:
http://soundcloud.com/user4804191/riot-wip
"Just shoot for the stars" = "j uh s t shu t fo o3 da s t a a3 z"
tl;dr version -- Two separate R's -- Japanese and English. Also a few extra standalone vowels. Standalone consonants if you can.
Edit: Actually, and you don't have to do this, but I just wanted to add that my bank
also had VVs for the five Japanese vowels, recorded and oto'd kind of like VCV. But
you also have more two-vowel things like "boi" and I didn't have any of those.
Just wanted to point it out is all. Your reclist seems pretty good so far though
and I just wanted to give you some advice to give this reclist the little edge
it needs to succeed! I hope this helps :].