I just found this music video from 2003. Apparently, it comes with not only an alternate name for "Yamucha's" (飲茶) but also a Japanese name (やむちゃー'ズ). Unfortunately, searching the Japanese name in quotations only comes with worklist(s) of at least one Japanese voice actor.
I also found this Japanese website from the same era, thanks to the Internet Archive. Although it appears that there's nothing displayed past the welcome screen, if you hover over the empty space you can find character bios and a links page, at least.
I just found this music video from 2003. Apparently, it comes with not only an alternate name for "Yamucha's" (飲茶) but also a Japanese name (やむちゃー'ズ). Unfortunately, searching the Japanese name in quotations only comes with worklist(s) of at least one Japanese voice actor.
https://www.youtube.com/watch?v=zcFm9lzZQZA
I also found this Japanese website from the same era, thanks to the Internet Archive. Although it appears that there's nothing displayed past the welcome screen, if you hover over the empty space you can find character bios and a links page, at least.
https://web.archive.org/web/20031215222055/http://www.yamuchas.com/menu.html