Translating plant names from Chinese into English can be tricky.
Possibly whoever chose PLUM to translate MEI either hadn't seen the fruit or was familiar with one of the varieties of plum that have golden orange flesh and a slight golden tinge rather than being deep red or purple.
MEI is PRUNUS MUME
Notice the color of the fruit. Its not very sweet and is used for making plum and other sauces that require a touch of sourness to counterbalance sweetness.
I have no idea if there is an equivalent Chinese fruit to our purplish plums. Perhaps the LI plum is sweet.
There's a wide variety of Prunus trees grown in China.
I suspect what caused the confusion is the color of the flowers which range from white to pink.