Oh yeah, there are plenty of bugs in the original version of this game. I didn't introduce any (well, I did at one point, but was able to fix it). Here's the list of bugs that I remember. I asked my testers not to report them as errors with the translation patch, because I checked and encountered all of them in the official release, too: http://fwibby.16mb.com/
I don't intend to include any fixes that anyone might make for those bugs as features of this translation, as I feel that a translation should just be text edits only... with the obvious exception of fixing this game's credits.
I think that being able to see the credits is important, even if they're just in Japanese. The people that worked on this game deserve to have their names shown for their effort. As for translation, someone else already did that (http://www.vgmuseum.com/end/nes/b/goemongai1.htm). Note that the way their mock-ups look probably wouldn't be reproducible in the game, you'd have to make the text much smaller to get everything to fit properly.
That was me.
While the english text you see on the images was added with an image editor, I did get the original Japanese text to display correctly thanks to a hack a Japanese guy named Mini4Rider did for me in 2010. I still have the .ips file is anyone wants it.