And Martha's room doesn't have to be exactly lava. Maybe it's special effects to give a more industrial feel. And it could be taking using tubes, which complain less than slaves. And it could be lava, why not. Corna has some volcanic activity (Cauldron).
Also, nothing says that the E4 is a tower, after all, you keep climbing upstairs and you're always walking north. Maybe the building goes all through a hill, then has a bridgey part (Colombo's room) that goes from the top of a small hill (Perica's) to another mountain that happens to have a volcano and a manmade system that once canalized lava to Martha's room.
Then at the top of this mountain is the Champion's room and the hall of fame.
Cornian arquitecture is always very creative.
In fact, this is now canon. Even though the game's been made... how many years ago?
Cornian canon is constantly in flux - it makes sense.
You're right, there's probably going to be at least two more updates to wrap up the post-game content.