I had written it in another thread, but to summarize on Elpis:

I felt it was fine ultimately, but yeah… timeloop shenanigans are not my favorite thing.

I think I would have appreciated it more if it were modern day Elpis being maintained by automata, and the actual story content being played out via echo flashbacks. Scenes where we need to be a character we could have just been Azem.

All that said, maybe the writers did indeed choose the best route because the Kairos Machine is going to be important in future content related to the 7th calamity. (Why nobody remembers what happened after Bahamut). Even then, it feels more like the writers decided to make that a big deal to allow for the Kairos Machine in the first place.