The sentence isn't entirely correct. I don't know what it said in Japanese, but maybe you can change it into "... banana hat of yours with gunpowder..." or "...banana hat of yours so it'll be bursting with gunpowder..." or something like that, so it'll flow better (first image).
Again, not 100% sure, but I think "a" should be placed between "than" and "coincidence" (second image).
"same world as I am" (third image).
I think it should be either "have they left?" or "are they gone?" (fourth image).
I'm honestly not sure whether this one is right or not. I've never seen it used like that (up all over the place). I think "up" is redundant, but I'm not sure (fifth image).
I think this one's either "open it" or "get it to open" (sixth image).
"Axel, don't let him "lead" you into something you'll regret" (seventh image).
I think it's supposed to be "nothing to be done then" (eighth image).
The "no" option isn't visible here (ninth image), however you are able to select it (tenth image).
There's a savepoint in the back of the Mai Tierra/Neverland right after you fight ArcGain for the first time and get Axel/Alfimi (eleventh image). It's to the right of Dr. Marion's location. The location when viewing the savefile is in Japanese (twelfth image).
I believe "to" should be between "happen" and "know" (thirteenth image).
Also, if I'm nitpicking too much about the dialogue (first eight images), then please tell me and I'll just ignore stuff like that.