As I\u2019ve mentioned before, I learned Japanese through classes that were derived from a program meant to train spies and diplomats, that put a lot of emphasis on linguistic \u201cpassing\u201d. Part of this was every weekday I\u2019d go into a room with 7 other students and spend an hour speaking Japanese, presided over by this sweet, grandmotherly woman who would just look disappointed in you if you fucked up.
(This was on top of 3 lectures a week and an hour or two in the tape library every day.)
As a result I instinctively speak Japanese words, even appearing as loanwords in English contexts, with Japanese pronunciation. Like, in order to speak them the \u201cAmerican\u201d way I have to actively try, and it seems weird to actively try to get shit wrong. I\u2019m afraid it comes off a little poncey.
The interesting exception is words I picked up before I studied Japanese - I still pronounce, say, samurai or karaoke in English the same as everyone else.