I think a timeline split does occur following Wario Land, but the "main" timeline (where most of the games occur, including Warioware) is the one where he gets enough money to obtain a castle. He later loses the castle at the start of Wario World and the spritelings were incapable of restoring it, hence why we stop seeing it.Interesting concept there. Certainly tries to explain why Wario is living in a house in some games and a castle in others. A bit complicated though, in how it turns a simple franchise into some sort of branching epic.
Then again, it also seems to be a pastiche of the Zelda timeline from the Hyrule Historia book, so perhaps the over complexity was the point of the whole deal.
You can not trust these fan timelines. buy the official Book of Wah and they talk all about it.Where's the timeline when " wario ends up emitting green house gasses and starts a global epidemic " ? I bet it all becomes Mad Maxx style world everything decimated by wario's fart's and they have to fight each other for gas in leather suits.