Throwing a burning torch into a jungle certainly won't lset it alight. But magical fire probably could.
Is the fire in Erebus magical? Certainly, the Fire I spell is, but that only creates smoke. Is the subsequent fire still magical? What about the raging, continent-wide forest fire 50 turns later? If every fire is magical, then yes, jungles should burn. If the spell is magic but the fire is mundane, then I don't think jungles should catch fire from adjacent burning tiles (Fire I is still okay, though).
Note that I'm not arguing for a gameplay change, just an exposition on the conflicting logic of physics and magic.



I'm used to playing in the DLL and assuming all the differences in the XML were caused by other people