Bring back Emet-Selch

[Iscah]

Memories are a strongly tied to the soul as we discovered with bringing the scions back from the First. Kairos was designed to erase memories and outside of Hermes we're not shown anything to indicate that Kairos has that effect. In the same way strong memories can keep a soul from moving on we can probaly say that memories can function in the same way.

Not shown anything to indicate Kairos has which effect? If (as your sentence structure implies) you are saying that we're not shown other examples of it erasing memories, then that statement is easily disproved, so most likely you mean no other examples of burned-in memories emerging from reincarnated Kairos subjects. In that case, Hermes is the only example of it happening but also the only possible example of it occurring because all of the others known to have been subjected to it – Emet and Hyth – have not yet died and been reincarnated to test whether they also retain and dream of those memories.

What we do have is a lot of examples of people who have been reincarnated since the Final Days and were not Kairos subjects, and there is no widespread phenomenon of people having dreams and visions of their past lives. While that is not definitive proof against it ever happening, we don't have any proof in favour of it, and the game itself ascribes a different reason for Hermes' dream.

And if you have to preface something with "probably" then you're speculating. It's not fact.

Also amon doesn't have clear memories of a past life, aside from the ones that reside in the Fandaniel crystal. Before he got that he does say "Night after night, the faceless multitude. The voiceless cries. Shards of shattered memories. But slowly the fog bangan to clear. This was Elpis and I...I was Hermes." Now that he's dead he was able to fully recall what happened

That quote from Hermes is entirely about the memory he retained because of Kairos – a recurring dream he had over and over until it made sense, and then he got implanted with the Ascian memories that completed the picture besides this one retained snapshot.

He outright says in the scene you are quoting ("Her Children, One and All", cutscene #1) that being granted the memories of Fandaniel that he knew his visions were "the memories of Hermes, that he himself erased using the power of Kairos". Not all the rest of his memories, just that one segment.

Logically the second-hand "memories of Fandaniel" he received upon being turned Ascian would contain Emet's altered memory of how he recruited Hermes and there was a mishap with the memory-erasing device, and Amon would realise he is clearly holding the missing piece of that puzzle.