Don't you love those translated manuals! I wonder if you will really be worried about plug colour after being stuck in first gear for several hundred years. There are some wonderful Chinese - English instructions on various products, makes using some household products very interesting! eg: Don't put to flame! Cover to preserve good health! Dispose of in friendly way!I would say the compositor cocked up that paragraph and got his lines mixed up or jumbled the lines when keying it on the linotype machine.
Best one I have read was in a motorcycle instruction manual for checking the heat range of the spark plug. It suggested to ride the bike for several hundered years in first gear, remove the plug and compare the plug colour to the chart attached. Sort of lost something in the translation from Spanish.