I don't think it was a joke phrasebook - that article you linked to is a serious study of it, but it is a bastardised pidgin form of Japanese, enough for traders to get by.
Read some of the later pages, and the intro as well. It becomes painfully obvious that the book was a joke, but it also does shine light on the local pidgin dialect.
This is classic:
On page 21 of the book.
"You must make less disturbance driving nails into the wall, or I shall be obliged to punish you"
In "Japanese" : "Oh my pompom bobbery wa tarkshee pumgutz"
Also "Perambulator" (baby carriage/stroller) - "Baby san bashaw"
Also, this very important phrase:
" The great depreciation of the value of the paper currency value of the Imperial Japanese Government renders it impossible during the prolonged absence of my partners to accept your tempting offer"
"Kinsatz yah dai oh Dora your a shee"