That would have been the case if they were neighbours and Romania was not NATO..
But look where Romania is located?
If you come by Sea China will automatically run into Turkey and Italy including the smaller nations surrounding there even Ukraine from the North and Poland including Germany and NATO forces stationed in the eastern European plain hence it is not feasible for China to come from the sea..
But Via Russia if Russia Takes Ukraine entirety then realistically China could fight a land war with Romania there will be a corridor but that would be fighting NATO on the eastern Europe teatre together with Russian friends and China's other allies this would be WW3.. Will China's team win it depends who are on their side if it is only China-Russia they will lose but if they have other allies included they will have a chance.. If Afpak is deployed on the Eastern European frontline allied with Russia, China, and North Korea and you can add Vietnam as for cannon fodders sake and throw in their the central Asia turkics then that bloc would not only stand a chance but become favourites to win