The keyword there is allegedly. We don't know how much of that is hyperbole. Keep in mind that certain Founders had a lot of trouble converting over (Tytlas comes to mind, though Verditius is also known to have issues). While I personally feel the Founders were by no means set atypical, that is not set in stone. And that's assuming that the story of the First Tribunal is accurate.
Considering that this thread is about exploring ideas for alternate histories for the Order, that doesn't have to be true. Maybe the entire Order was originally created by Triamoa and Veia to serve as a tool for their vengeance against their father's murderer's and their mother's people - the Amazons. Not likely, and utterly unsupported by canon but there is just enough available information that it makes a plausible story, and one heck of an interesting saga.
The idea that the order may have been created for an agenda could work really well actually.
- The Houses could serve as a (crude) kind of specialization. Verd for enchanting/armament, Jerb for for mundane relations, Mert for fae relations, Gurn for security, Boni for research, Merc for admin., etc.)
- The Code's requirement's do not lend themselves toward an expanding populace. It's unlikely that this was deliberately ignored, though the Founder's could just be less wise than supposed.
- The First Tribunal and the Founders serve a very symbolic role. It wouldn't be too far fetched to believe that the story was concocted to conceal a less pleasant origin.
- If it happened, it is unlikely to have been the romantic, idealized way that most seem to believe it was. This was a meeting of disparate, suspicious magic users from different traditions, mostly bound together by the fear if they didn't learn this 'Parma Magica' their enemies would walk all over them.