On Themis [6.4 SPOILER]

[MikkoAkure]

It's more like a flashback then time travel. You lack the ability to change the past when the echo triggers.

1.0 Echo usage leaned more into actually being present in past events, Ul'dah's time travel opening being very canon and Gridania's being mentioned in passing. Limsa Lominsa even had a whole full CGI cutscene where Y'shtola uses her mysterious powers to send us back to the present before a tidal wave crashes onto the ship. The city storylines in 1.0 revolved around going back in time and interacting with people in both the past and present to solve a mystery in each one. Limsan PCs got to interact with Rosensthal before his fall when he was still Sthalmann, Gridanian PCs got to interact with the original Yda, and Ul'dahn PCs got to be a part of Minfilia's origin story and interact with young(er) F'lhaminn and her then boyfriend.

Though it still remains to be seen how much of 1.0 and the Echo powers used were canon for a WoL from back then, we know that a lot that went down in the time travel cutscenes are still canon. The Echo may not act the same as it did then for us now, but I'd like to think that they can still have it do that for future content that isn't written as confusing as 1.0 was.