Yes Alexander could alter the past if it wanted, and did alter time one time too.
If Alexander hadn't popped into our time line at the spot it did and stopped the Illuminati. The Illuminati would have gone on a changed time.
Alexander changed time once under Alexanders own will and stopped the illuminati from happening the reins of time.
If the WoL/D has time travel. The antagonists have to have a greater control over it or there is nothing for the hero to rise up to beat or no threat to worry about because time travel.
If the ascians had time travel the would change time for the worse. they see reality as horribly warped already. they are eternal beings by all rights {unless unmade} they could go as far back as the wish and not run into any "grandfather paradox", they would just lop off the branches of time they didn't like.
If we had time travel we would change time, and by we I mean the players of their hero. If not you some would.
I have a few characters I've played out events in different orders.
Iscah while having a "time travel agender" is working the principle view that time has to be set in stone and immovable no mater where you go it wont change because it has happened, Consequence don't exist because they can't . Which is flawed to lock your view to when talking fantasy and it is fantasy.
Also there is evidence that this set in stone view is it not the case in the ffxiv universe and time branches around the WoL/D and is changeable because anything is possible to WoL/D.
Also that we don't need to have time travel added in a manor that prevents change because it already exists in the form of the ECHO
echo echo![]()
Then the fault lies in your explanation.
Try again, because you still have the same issues I see from the 1st time you tried to explain it.
"real world" events for 7.0 and on have yet to be written.
"real world" events for 6.0 are still being fleshed out.
"real world" events decided on happening in 5.0 to 6.0 could still change last minute.
Putting a future bubble in at 5.0 inhibits/stunts the writing choices of 7.0 and on.
Lets not forget
The concept of time travels fatal flaw being that.
You flog that dead horse! flog it!
Time for a GROUNDHOG DAY!
No need for a convoluted addition of time travel for Crystal Tower.
The cannon time line is as it was released. If you do it out of order your fault, also the echo fixes the issue anyway.
They won't add time travel to fix your preserved issue of Crystal Tower any or all reasons
◾they don't need to as the "leak" was false.
◾they can lock it into a clear condition. (1st 3 primal HM ARR)
◾the way its handle in the past with similar issues will continue and ignore the fact you have yet to do or have done (Estinien, DRG30-50, post HW / Nanamo ,end of ARR to when woken, CUL50 / Krile, Warring triad, mid-StB captive to zenos / Y'shtola & Urianger, Warring triad, post calling / Alisaie, post HW, binding coil / Alphinaud, binding coil, post becoming an envoy for Doma / Nero, after omega story arc, Crystal tower) leaving "you forgot" or "the echo" the answer.
Maybe all they'll do is a dialog addition if you haven't clear Crystal Tower where G'raha Tia may say something like "What is it friend you act like its our first meeting don't tell me you forgot the adventure we shared traveling to this tower an on to the world of Darkness, jog your memory?"