The Izunia explanation is honestly the only thing they could have come up with to explain the localization discrepancies. XD;
As for Ardyn submitting, he says in the credits that he intends to kill the True King and bring about everlasting darkness, so I don't think we're meant to see him as getting what he wants either way. The difference is primarily in how vicious Bahamut gets with him, not the final outcome of Ardyn's mental state.
(Though I suppose it could be that part of Ardyn was willing to submit and the other part couldn't stand to let Bahamut succeed? I guess that could be a possible difference too, if "reject your fate" Ardyn has completely squelched the part of himself that was willing to die.)
I think in that particular moment (due to the hurt being so fresh) and on the surface in general he displays strong feelings of wanting to fuck everyone over but in the end deep down he's also probably just tired and wants it to end and I don't think Ardyn really gives a shit as to how it ends by the time he faces Noct. Under all the layers of trauma there's gotta be a glimmer of the old Ardyn who just wants to move on and rest considering that even after the 2,000 year imprisonment he was still thanking the gods for the food on his plate and objecting to Verstael's suggestions of revenge. It isn't until after Verstael relentlessly egging him on and his fight with Ifrit digging up all of his repressed trauma that he begins to indulge in the idea of revenge again.
He seems like he's just doing everything just for the sake of doing it and getting it over with by the end. Considering it's been like 40 years since Bahamut's revelation to him when the main game happens his rage probably isn't burning as intensely as it used to in Episode Ardyn. Even the most petty person's anger eventually subsides with enough time.
The reason I say this is because:
1) Despite him seemingly declaring that he hates Aera for lying, when the moment comes to kill Luna (who looks just like Aera) he shows some hesitation when she starts speaking to him and he has what seems like a moment of self reflection but of course he's too far gone at that point and he's gotta see things through so he slaps her aside and puts on the villainous madman facade again and pushes onward.
2) Despite saying he'll lure out Noct and kill him Ardyn doesn't strike him down the first chance he gets in order send a big old "fuck you" to Bahamut which would be the most logical course of action for someone who doesn't want to play by the rules anymore. Yet despite the fact that at the end of Episode Ardyn he never makes mention of wanting to fight Noctis at full power he still helps him out a great deal and I think it's fair to say that without Ardyn intervening at certain key moments Noct would've never even made it to Altissia let alone to the Crystal. He doesn't ever go out of his way to kill the bros either and none of their major injuries are inflicted by him. He just torments them enough to spur Noct on but right up until the final fight he never kills them to try and break Noct despite it being really easy for him to do so. Even Luna can't be considered a direct kill of his as a stab wound in the stomach can be treated if given care in time. Luna's death actually comes at the hands of Leviathan's temper tantrum. Really, Ravus is the only one he actually ends up killing with his own hands out of the whole main cast. Everyone else is just a casualty of Bahamut's plan to have him spread the plague until Noct stops him.
3) Lastly, in his final moments there seems to be a mutual unspoken understanding between the him and Noctis. He even courteously greets Noctis in the afterlife before the final blow and goes from the physical world rather peacefully too. That, to me, screams that he's ok with just going at that point regardless of whether he won or lost in the end.
Just like people in real life I think Ardyn had a lot of clashing feelings and despite him outwardly becoming the villain everyone wanted him to be I don't think the gentle soul of a healer every truly left him, it just got buried under a shit ton of baggage. Think of it like Darth Vader being angry his whole life and his rage being the strongest when he was first betrayed but deep down Anakin still lives even if barely. In the end those little bits of Anakin Skywalker shine through again when he meets Luke but despite him wanting to be with his son he continues on his dark path because that's what the world turned him into and he's too far gone to really turn back from it all so he suppresses it until the final moments where he's just so tired from it all that he goes out being his old self again. Ardyn's old self shines also through ever so slightly as the story begins reaching its end imo and by the time of the final blow I think he's not going out as the King of Darkness anymore but as tired old Ardyn.
Also just my personal head canon but I'd like to believe that the alternate title screen after completing Episode Ardyn is him finally having his peace with Aera in the afterlife just like Noctis and Luna. Both of them are even sleeping together as a parallel to Noct and Luna.
