Yeah, between that and the US voices still having the same 'types' of issues people noted in the trailers and previews, I'd say it's probably safe to say that the delay was, at least in part, just wanting to escape the crowded release window.'
YMMV, but even aside from last-name pronunciation issue, I've noticed some clunky delivery from the English VA watching some streams (of which I don't particularly remember in P4 outside of P4g add-on stuff)
Sure, some of that's probably on the translation itself, but I've heard some funky inflections and tones that don't match the scene.
Not all bad, by any means, but IDK about 'stellar' - though granted, that's based on 5-6 hours of watching streams, rather than the 100ish hours it'll take for the full game.