Well, definitely sometimes it's indistinguible so we could use Roman/Japanese chars following your standard (that's usually used). But when they are distinguible I think we should keep them like they are for accuracy. For example, it's not uncommon to see "roman chars、roman chars" with a Japanese (inverted) comma, I don't think we should 'fix' it with regular commas since they are not 'wrong'.
Also remember many tracklists here are copied from official sites and such and are fairly accurate (many others are still incorrect of course). In your .hack example, indeed it's impossible to tell them apart (I'd default to Roman anyway). But in the
official site they use Roman letters and the scans in both releases seem to use the same font, so I'd fix the limited edition with Roman letters (but if the official site said otherwise I wouldn't). Same with the track "ev19＿1", due to the monospaced font it's hard to say if it's a _ (roman) or a ＿ (Japanese), but since the official site uses _ (roman) I'd change it too.
Oh and I'm not saying we should use this or that in our tags, just that imo it's better for accuracy reasons to have it here as close as it's printed then adjust, just my opinion (this is all for Japanese tracklists, in case anybody is lost).