It's actually improved tremendously. PCSX2 has been making some big strides in recent years, and the latest release has fixed a few more quirks the games had.
You can basically play 4-5-Zero without issue via the emulator if your PC can handle it.
Seconding this. PCSX2 is a pretty solid platform to play the AC trilogy, and has become a pretty good emulator in general. If you cant get og hardware, this is a more than fine alternative on any decent pc.
I’ve found Ace Combat X to be one of the most difficult in the series. Even the generic enemies are head and shoulders above the ace squadrons in Zero and will absolutely wreck your shit.