Answer: If the yellowing is on the lowest (oldest) leaves, I don't think it is anything to worry about. As your palms develop new leaves, the oldest ones will yellow and die.
If the yellowing is on both the oldest and newest leaves, it's possible your palms are just showing a little transplant stress. As soon as the roots become established, they'll begin to put out healthy new fronds.
Palms prefer an occasional deep soaking rather than frequent shallow waterings. Since your palms are planted in a lawn area, they'll have to adjust to the sprinklers - but you'll be doing them a favor by watering them deeply once each week during their first growing season. This will encourage deep roots which will help anchor the palms in the soil.
Best wishes with your palms!
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