I noticed that a few artist tags have Latin lettering done via Shift-JIS encoding. This additionally makes it impossiblew to pick up in search unless you were to copy/paste the letters from, say, a table or something.

ＡИＯＮ
ＵＲＡ （ウラ） (a "dead" tag that has no images assicated with it)
Ｎ.
ＮｉＨｉＫｉＨｉＯ (One that we already have a tag for)
ＹＵ☆３

Would it be worth it to go and redo the tag names so that they utlize lettering that we can type up with our own keyboards?

Yes.

I wish you'd have linked them here, lol.

Edit: Done.