Unfortunately the most advanced/impressive ones are the ones people aren't allowed to talk about
There's many cool projects being worked on for the military and aerospace industry, hence the nda agreements.
The highest level of accuracy job I worked on was TIG welding the engine shroud for space rockets.
This involved some 5000+ (yes five thousand) 50mm / 2" long welds, all with laser search/tracking,
automatic exchange of torch neck / tungsten electrode, tcp-calibration etc.
Another fun job was welding valve seats for marine engines, so we're talking BIG valves.
The program was created so it was fully parametric and in the end the operator had to enter a
"recipe" with ~8 values and the robot would take care of path generation, multilayer, searching, etc.
Biggest one is probably a project with three inverted robots mounted to its own Gantry with a 4m hoist/elevator,
3m slide and a ~30m track. Two 10T single axis positioner with a height/length adjustable tailstock and a 5T 2ax positioner.
All in all, 33 axis ( not on the same controller though ).