I don't know much of the inner circle (non elected people) so I can't comment on them.

Would someone who hates Jewish be a sponsor for a motion such as this?

https://edm.parliament.uk/early-day-motion/40500

It didn't happen obviously because brown was on his way out and the incoming conservative party was obsessed with immigration numbers and saw that issue as their primary vote winner.

Corbyn is a poor leader and probably has quite entrenched views but the idea that he is personally anti Semitic or racist just doesn't stack up.