Waiting location for Amtrak/Greyhound connecting buses is unclear. There are two sides on W Grand Ave across the rail tracks. Is it on the westbound side (in front of B.J.'s ATV), or the eastbound side (in front of Station Grill)?

In front of Station Grill.

It's actually behind the Station Grill. Enter the driveway next to Station Grill, and go straight. There should be a little green bus shelter with two benches. The bus driveway runs parallel to the rail tracks, but the bus and train waiting areas are separated by not just the rail tracks, but also the restaurant's patio, its parking lot, and also a wall. The train station is visible from the bus area, but the bus area is behind the patio and wall when you're on the train platform. (Finally found out after missing the bus)