Something I don't get with Summoner, X of Swords and the timeline of Arakko/Amenth

So despite reading X of Swords, loving it, and going over it more than once, I can't seem to understand the timeline of Arakko falling to Amenth.

So we see in X-Men #14 that when Arakko was close to falling, they opened a rift to Earth and sent Summoner and the Arak Coral to Krakoa in order to warn Apocalypse and ask for help. We see this from Summoner's point of view in X-Men #2 when War tells him to hurry as the armies of Amenth are getting close.

But when Apocalypse opens the External Gate and sends Summoner, Banshee and Unus through, only to find an Amenthi army lead by the Four Horsemen waiting for him, it's revealed that Summoner has been lying to them all along and luring them to open the gate so that the armies of Amenth can reach Earth.

But how does that make sense? Why would Summoner betray them? Even if we assume that War contacted him again and told him "you know what, we've surrendered, forget about asking for help, just get Apocalypse to make a gate so that Amenth can invade", why would he agree to do that? He seemingly came to Earth to save Arakko, why abandon that when it ostensibly needs saving more than ever? Is this just a continuity error here? Also, Genesis states that the Summoners school of magic was born from Amenthi/mutant hybrids and she only learned of them after dueling Annihilation, by which point Summoner was already an adult. And if Amenth and Arakko didn't unite until after he left, it makes no sense that he would have become a Summoner before that.

Aside from that, I'm having trouble wrapping my head around how long Arakko was under the control of Annihilation. By the timeline presented, it seems to have been just weeks, maybe months tops, because I don't see how much more time than that could have passed between X-Men #2 and X of Swords. But by the way everyone on Arakko acts, it seems to have been years. The Horsemen and all the other Arakki don't question what they're doing at all. They're not the least bit reluctant to be throwing away millennia of war against Amenth to destroy Earth. This would make sense if they had spent years under Annhilation's sway, but not weeks or months. It feels like it would have come up at some point.

When the Horsemen are besieging Del'dilor, they speak as if the tower has been known to them for a long time, when the portal to Dryador was seemingly opened the same time as Summoner was sent to Earth.The White Sword mentions defeating the Horsemen time after time and knows they've submitted to Amenth, but how would the Horsemen have had time to lead multiple attacks against him in weeks, when they busy conquering Dryador?Isca mentions that the Great Ring has ruled Arakko for millennia with the exception of a period she calls "the fallow years". It makes sense that this would refer to when Annihliation ruled, but how could that have been for years?

I know I'm reading way too much into this, but I was just hoping someone else could make sense of all this, or knew if Hickman or any other writer had addressed it.