I don't understand your post OP.
You wrote: I am specifically referring to graffiti etched on desks and messages exchanged on social media, in addition to views overheard by or expressed in front of educators.
Messages on social media should be leadiing to punishment from school, its illegal to post hate speech, simple.
Views overheard in school should be leading to punishment , simple.
Graffiti needs to be removed at once and it made clear anyone caught doing it will be suspended.
What's to discuss?? What's your school policy on hate speech? The The Racial and Religious Hatred Act 2006 is pretty clear on this. All your children under your care are over 10 and so have reached the age of criminality.
I'm a black parent and send my DC to a private selective London day school (non-denominational) which has a real mix of races, Jewish, black, South Asian, Far East Asian and white British and white European. Your post reminds me why I find the fees to go private.
The school celebrates all cultures and has a zero tolerance to racism , its a simple formula that seems to work. The key is zero tolerance. If a child was openly antisemitic in front of a teacher, fuck, they'd be strung up. Racist graffiti would be a MASSIVE deal, as would racist social media posts, that a teacher was aware of.
Local Jewish groups would be VERY receptive to organising talks and visiting places of worship, go for it. Just as a Vicar or any Christian organisation would hardly decline an offer to talk to children. If you get kick back from parents ensure it's presented as a whole term of cultural events, people from Sikh, Jewish, Catholic, Muslim etc. But frankly why should you be accomodating parents with disgusting views??
You have to challenge anti-semitism in all its form, every single time.
Why not start with a school trip to the Jewish Museum, (if you're in London) they can help plan a school trip.