I hadn't seen those chips yet. But you're right, they have Vbat functions.
Still can't get microchip.com to show them or any other 18F's with a search for Vbat.

I asked about the J94's here, and the response was ...
The J94 series was scheduled to be added in the last update of PBP3, but some issues came up with the device that requires new library routines.
Hopefully, that will be completed by the next update of PBP3.