I won't insist.
But in our dojo we do also wear funny clothes, bow in, and greet each other in the beginning and end of class in Japanese. Our basic rule (not followed very strictly) is that whoever teaches that night is called sensei. Doesn't feel any odder than those other random customs we follow, to me.
I wouldn't regard any of the above mentioned as random customs. They are all part very important part of the training IMO. So is training under a "sensei".However, training under a "sensei" and all that entails, is very hard (although by no means impossible) outside of Japan because of the cultural references. If it"s just a title of address, you could call your instructor anything, surely?