Yes, you're right about this as a French and a Jewish surname. This is what Jean Tosti has to say about the French Bondy -
"Le nom de famille est surtout porté dans le Centre (36, 37) et dans la Saône-et-Loire. Il devrait s'agir d'un toponyme, apparemment sans rapport avec la commune de Bondy (93), qui désigne le domaine de Bonisius (nom de personne latin). On pensera plutôt au hameau de Bondy à Saint-Gence (87), et à celui du Bondy à Ouroux-en-Morvan (58). Sens incertain : peut-être une retenue d'eau (voir aussi Bondie)." (
www.jtosti.com/noms)
So there are several possible place name sources.
As a Jewish surname it's connected to the suggested Spanish origin, as I've found the name (Bondi and Bondy) on a list of Sephardic Jewish names in Poland. So I'm guessing it was probably Bondía or Bomdia (Portuguese), meaning "Good Day". This would be a translation of the Hebrew Yomtob/Yomtov, a name whose exact significance is not clear to me though I believe it's religious. Not Slavic then, but derived from some Romance language.
There is also supposed to be an English surname Bondy, an alternative form of Bond, but if it survives it must be very rare.