According to elmer though: "Every scene that is voiced also has a message box with the text of the speech inside it.", meaning there's no need for dubbing in this particular case, unless they really want to do it additionally for the sake of completion, which is what I was referring to (assuming the space limitations don't prove to be overwhelming). There are a few other PCE-CD games like that from what I recall (Dragon Knight 1 & 2 come to mind right now, we wanted to work on them at some point).
Black Tiger mentioned The Apocalypse IV for Saturn/PSP; that one had some voiced cutscenes without subtitles, as far as I recall, so it probably would be more of a pain to work with. And yeah, there are lots of songs and puns in that game, so that would likely be an interesting localization effort, but a rather difficult one nonetheless.