My brain is resisting with some of what you're saying, which is a good sign. A sign of what? I don't know yet, so here we go.
With dissonance, I believe there's a clear delineation with how the show approaches the narrative aspects, specifically season 1 in comparison to season 2.
Let's take the first time we actually get to witness what could be a full on psychotic event for Kevin in season 1. That occurs in the finale when it appears as though Matt commits Kevin into a mental hospital. There is a plausibility to that event. Upon "waking up" from that event uncertainty and ambiguity arises as to whether what we just witnessed was real or a psychotic event or maybe it was just a bad dream. Even the song in the background during the diner scene is called “Sleepwalk.”
The second time we witness an event like this is in International Assassin. The event has no plausibility in the real world. You can't question the reality of it because it isn't real. It’s either a psychotic event or there really is a purgatory-like place. If the former is true then that defines these events and they are no longer ambiguous. If the latter is true now we have to contend with multiple levels of realities or separate dimensions or whatever you want to call purgatory. This compromises the ambiguity set forth in season one.
The dissonance:
The first scenario can be based in reality. The second cannot.
Because these events no longer have to contend with reality, this gives Lindelof carte blanche to write any scenario and the logic will give credence to the arbitrariness. It doesn’t matter what the scenario is. It could be hijacking an airplane, killing a dictator in a communist banana republic, or singing karaoke in front of God in purgatory. He can create any scenario he likes; they’re interchangeable; they make no difference; they are arbitrary.
There isn’t even a consistent reason for him to visit this place and what he has to do in order to accomplish his goal. The first is to defeat Patti, the second is to return home, the third and fourth is to prevent a flood.
At least in the case of defeating Patti, the event and the goal are related. If you believe that Patti is a manifestation of his psychosis, and that the hotel is a manifestation of his psychosis, then the event and the goal are related and resolving the goal is plausible. If she is a ghost haunting Kevin, and the hotel is purgatory, then the event and the goal are related again and resolving the goal is plausible.
That logic doesn’t carry over to the second time. If he’s having a psychotic break, why would singing a song about going home have any relation to him surviving a gunshot? This can only make sense if this place is purgatory and God is testing him to send him back to life: the event and the goal are related and resolving the goal is plausible, but then the event is being defined as such and it betrays the ambiguity.
In questioning these inconsistencies, one could invoke the mantra, but then that’s just hacky and contrived.