100% agree with you. Last year I have talked many Japanese forums about her includation they said she appointed a Japanese translator in Japan that is why av campanies easily book her for new scenes. Many western adult actress don't want to do av porn in Japan that is the reason they only book Melody Marks. She is popular in Japan already.
Travel and costs, probably. Melody films multiple AV DVD's during her multi-week-long visits, that's how her brand is sustainable in Japan, that's probably how she saves on cost, plus she already has connections to make sure she's as safe as possible from getting scammed (the japornxxx controversy aside)