Quote Originally Posted by Cilia View Post
tl;dr: Don't worry, a wizard did it.

When the dome appeared, time for the people in Yyasulani (and Zoraal Ja, who had gone over earlier) passed at an accelerated rate compared to time for the people outside of it. By completing Vanguard, a bridge was made that stabilized the difference (synched it to Source time).

Don't worry about the how or why of it; it happens however the writer wants it to.
Always remember the main rule of time travel:

Time travel works how the story needs it to work this week.