User blog comment:Omega natsu2/Fairy Tail Episode 217: Celestial Spirit Beast, Review./@comment-4933386-20150124072125/@comment-7418318-20150124112934

They said that the Celestial Spirit World and the Human World are flowing into each other at the beginning of the arc, so maybe the difference in the time-flow is also reduced or gone alltogether.

But I don't think the problem is too bad. Even if the time-differences are still there it'd mean that one hour in the CSW equals a little under 4 days in the Human World. Unless they fight for several hours, they'll only be gone for a few days, weeks tops.