Beastie and Hexley are not free culture: https://libregamewiki.org/Talk:SuperTuxKart
Maybe have a look at the Toots, Carrot and Sepia karts I made: https://gitlab.com/luckeyproductions/goodies/stk-addons/-/tree/master/Karts
Modanung
joined 2 weeks ago
BSD's Beastie is nonfree.