Board Game Arena

In the rulebook there is only one tiebreaker: the largest single connected territory wins.
However, it appears the BGA mod does a second tiebreaker of highest number of total crowns.
Where did that come from?

Don't get me wrong. I wish the rulebook didn't end with "Share The Victory", but I'm curious how and why this extra tiebreaker was added.

Because the English rulebook is wrong.

The French rulebook says:

En cas d’égalité, le joueur qui a construit le domaine le plus étendu (peu importe que ce domaine possède des couronnes ou pas), remporte la partie.
En cas de nouvelle égalité, celui qui a le plus de couronnes remporte la partie.
Si les joueurs n’arrivent toujours pas à se départager, ils remportent tous la victoire.

Which roughly translate to "In case of Tie, the largest domain win. If there is still a tie, the most crowns win. If there is still a tie, victory is shared".
If the English rulebook is missing the second part, since the creator of the game (Bruno Cathala) is French, it is the French rules that are correct and the English ones that are wrong.