Following up on yesterday's research, I remembered that thanks to a friend's inquest I came to own a scan of a 1922 map of the French Concession. At that time half the streets in there were only a blueprint. Here's a fragment of the that map. It shows the location of the park in question ("pépinière" is French for "nursery"), where Fred Richardson used to go. It shows that Anfu Lu and Wukang Lu were the earliest streets to appear in the west French Concession, while Wulumuqi Lu, Hunan Lu, Tai'an Lu and Fuxing Xi Lu were only in the making in the year 1922.