One brakelight out - all others are good

No separate fuses but the RH side does use a separate ground.

The manual sucks about that, but they're located in the bottom of the triangular box in front of the IPDM (red arrow). It's a complete PITA to get at them. You need to remove the cable restraints at the front of the box (black arrow), lift the harnesses, then undo some of the connectors at the top of the box. Once that other stuff is out of the way, you'll be able to see the relays buried in the bottom of the box.