I am also interested in learning Chinese and Japanese enough to read mathematical articles.

While also learning basic language notions with traditional courses, I am practicing by reading small and elementary mathematical wikipedia articles in english, chinese and japanese, that I sometimes translate back with google translate to match with the english version. I making slowly my own quadri-lingual dictionary (with english and french) with an electronic card system (Anki), so that key hanzi/kanji for mathematics allow me to progressively guess the subject of an article for instance. I devote some time to writing correctly by hand each new characters many times to reinforce memory by gesture and concentration.