There seems to be no positive identification of these spoons as yet.
On the spoon shown, in the large shield above “NAGASAKI” is 福寿, “good fortune and long life” or “luck and blessings,” a common enough phrase in Japan but in this case probably imitating similar CES spoons. Indeed, the flower in the interior of the bowl is a plum, while those beneath “NAGASAKI” are cherries. Traditionally, in Japan the plum represents China and the cherry, Japan.
The symbol in the small shield beneath “NAGASAKI” is an old-style hiragana ゐ(phonetized, i), which went out of common usage around 1910. As it is not found on all of these spoons, it might be one retailer’s mark.
Labor was cheap and plentiful in pre-WWII Japan, so manufacturing inexpensive spoons in Harbin and then shipping them to target markets in Japan would have been commercially disadvantageous. (I cannot imagine there would have been a great demand for spoons bearing the names of Nagasaki, Moji, or Yokohama among either residents of or visitors to Harbin, and I know of no such spoons bearing the name of Harbin.) Given the variations in the design and markings, they were probably made by several local cottage-industry metalworkers subcontracted by one or more retailers. As late as the 1980s and beyond, Japan’s major cities had large semi-industrial districts filled with such small businesses usually run by a family living in an attached home.
Cheryl notes that the design of crossed Japanese and American flags would have appeared during the heyday of amicable relations between those two nations (roughly, 1905-1925). I agree that their production probably began around 1900 or shortly thereafter. Most of the 84 marks I've seen on these spoons appear to be part of the mold (that is, the design) rather than punched. My current theory (to borrow Cheryl's word) is that the Chinese motifs (plum, "good fortune," the dragon finial) as well as the 84 mark were loose references to the two foreign countries most familiar to Japanese, thanks to the 1895 victory over China and 1905 victory over Russia, and that the romanized spellings of the port cities would have augmented the exotic allure of these souvenir spoons for Japanese visiting these places while also appealing to the tourist trade.
The end-date for these spoons is probably around 1930, when the Japanese government began implementing a national system of hallmarking. Furthermore, nearly all of the small metalworkers throughout the Japanese Empire were pulled into munitions by 1938.
Hopefully contemporary documentation will eventually come to light.