When Tom is inside the whale's belly, why is it that Sinbad and Job are speaking in their native tongues, thus making Tom unable to understand them, but Baron von Münchhausen and Pinocchio are speaking in English, instead of German and Italian? The explanation can't be that Tom knows German and Italian and we're just dealing with Translation Convention, since Münchhausen, Pinocchio, and the Scottish fellow are also able to understand each other. The Baron probably knows English, but it seems unlikely that Pinocchio would. The whole thing takes place inside the "story world", so why not have everyone speak in English, since the stories of all these characters have been translated into that language?
Maybe Tom is more familiar with the stories of Pinocchio, the Scot and Munchhausen, and never really paid much attention to Sinbad and Job. Maybe because of that he is able to understand those 3 in the story world and not Sinbad and Job?