This part seems to eliminate most, but not all, "accidents." For example, I'm cutting a limb off a tree on my property, and it falls on your car. Cutting a limb off a tree is not a sinful action, so this doesn't fall in the definition of "Unjust Damage."
On the other hand, if I'm driving drunk and run into your mailbox, I think that would fit the definition - even though I didn't intend to hit your mailbox - because drunk driving is a sin.
Good analysis.
I was also thinking of posters on FR who may say something about Catholicism out of ignorance and intend to not even hurt Christ or the addressee. On the other hand, there are posers who deliberately know they are slandering or blaspheming either the individual, a saint or the church when they post.