Everyone in here with the "10 year old game" and expectations of ease of porting what is basically the PS3 version (not the 360 version) to modern systems with the very high likelihood of mangled code. I'm not saying it's a thing to sweep aside, but you've got a Japanese dev porting a previously Japan-only version of a game where the lead console being ported to performs better than the others. they probably, basically, ported the PS3 version to PS4 then ported that to the Xbox and Switch, hence the lack of 60fps outside of battle (whether it matters or not is up for debate).
The "Max 4K" is probably "up to 4K" and that's as far as they tested because the people running it above that are incredibly few and far between. I'd be surprised if the number of people getting this more or less at launch and are wanting to play higher than 4K (read: at 8K) are in more than double digits.