I left the French ones "untouched", they were like this in Japanese edition. Artist's choice, Kumeta-sensei seems fond of French in BokuSeki (like, the titles of special booklets are also in French).
@Nanamka Too bad that french editors don't love Kumeta-sensei's work, Bokura no kiseki is still not published in France. That's pretty rare for a manga this long. I would buy the hell out of all the volumes available.
@Ameena07 I may translate some more parts of it, but I don't plan on making more scanlations from guidebook... it's one hell to translate and hard to edit. So maybe some snippets, trivia, interesting info, but not whole chapters.
I love these guides and charts the author adds and the foreshadowing of stuff that's about to happen. It really helps with my goldfish memories when there's so much characters, agendas, and mysteries.