It's only the first 3 games. Essentially, three teams have to do a back-and-forth between continents. I'm sure it'll be set up to give them a bit of a longer break after the initial match to readjust. It's really not that serious.
Even for the three host teams, it will be less than ideal to have to travel from their home country across the sea for the rest of the tournament.
Usually teams travel to the host nation well ahead of the tourney to whatever hotel/training facilities they booked and start training there.
In this case the three host nations in South America will either have to do that between their first and second game or they have to travel to Spain/Portugal/Morocco beforehand and do the same back and forth as their opponents.