Interesting, Shanghai (est 1958) is believed to still coat in China, having moved to a new factory c2016 and scaled up production mainly for Xray films which are in demand in the home market with a big push on improved medical facilities. However GP3 was only ever produced in 120 and sheet form and maybe the GP3 emulsion isn't really suited for 135 and its smaller image size.
OrWo don't have their own coating facility (the original facility being a museum now) and one understands is currently coated by Foma? and before that Forte (at least people have reported receiving OrWo films by mail 'direct' from the Foma factory). So this suggests 135 bulk rolls being imported from Foma to be packaged in China. The UN54 markings suggest that it is probably UN54 (I presume they mean edge markings and that 'paper' is a poor translation for film). If it was a bespoke coating of any scale there would presmably be no reason for it to have UN54 markings.....