I wouldn't say it's a lottery.
In my experience a pilot who comes here with the attitude he/she knows everything and is going to teach the Japanese a thing or two about aviation will have major problems.
A pilot who comes here and accepts from day one that it's their airline, their rules and procedures (no matter how silly they seem), that they're in a foreign country and puts in a reasonable effort will generally succeed.
ATTITUDE is more important than anything else in Japan, no matter what you're doing.