The satellite image is from Google, but the road data is from OpenStreetMap.org — Google has not been updating their maps for China for years now, as they have no mapping partner in China anymore.
There is a relatively new direct road between Qiubei (the county town a few km from Puzhehei) to Guangnan, which goes through sparsely inhabited karst land, no need to go back to the expressway. That road is just a bit over 100km.
Both busses will arrive sometime the next morning, I would estimate the travel time to be 12-15 hours: about 6-8 hours to Puer (Simao, all expressway), then another 4-5 to Lancang (a smaller road with not much traffic), and another 2 to Menglian (another smaller road, plus the bus might stop in Lancang for breakfast). Sleeper busses sometimes take their time, but you should be the
