FF2 has a nasty error which deletes needed hidden attributes on flamethrowers fully, and because of this flames doesn't have neither speed nor any gravity. I would suggest to you to use subplugin like
"juegos_flamethrower" or you can
manually add everything you need through rage_new_weapon.
Either way you need to check the overlay that is used in the plugin, and also add "rage_overlay" together with "juegos_flamethrower"/"rage_new_weapon" to fully replace Fujiwara's rage (because as far as I'm aware, rage "ep_radimoko" or how is it called comes with an overlay).