Yes but I didn't say "you can become fluent" did I? That would be the same as saying "you can become proficient". I said "you can gain reasonable fluency", which is exactly the same as saying "you can gain reasonable proficiency". I guess you haven't seen the word "fluency" used in this way before, but if you put it into Google you will get 1800 hits for "reasonable fluency", e.g.
"Japanese 3 is a continuation of J2 or the equivalent. Upon completion of this course, students should have acquired mastery of basic contemporary Japanese grammar, vocabulary and a total of 400 kanji with new readings, and be able to communicate in Japanese in everyday situations with reasonable fluency."
That is about the level you could get to in a year if you studied hard.