A quick google tells us that an independent witness says the kids were fine and just larking around.
Ive also heard that the pilot was pro-Palestinian with a flag in his cockpit but it’s unverified so taking it with a massive pinch of salt.
A Spanish transport minister deleted an antisemitic tweet about the children. No apology about this tweet sadly.
Given how Spain haven’t apologised for their shocking behaviour you’d think they’d be talking all and sundry if there were death to Arabs” chants
No official sources verify anything about chanting, they don’t even allude to it