I have never heard "bokuh" either and I am scratching my head at Schiller's attempt. My only guess is maybe he heard it that way sometime long ago before he knew any better and now his preference for saying it that way has become habit and he used it automatically even though he knows better. Kind of like how many old folks say "gee-sha" for geisha because that is how (as I understand it) many in the media would say it back in the 50s.

But yeah, I am the same as you. I have spoken Japanese for long enough that when I look at a Japanese loanword that has appeared in my English text, it is really difficult for me to see any way other than the Japanese way of saying it.

haha bouw-kayuh. If the Duke were a photographer.