your questions regarding the game rules (improving the interpretation).

Dark made a completely logical move by using wings,

Movement points are an important resource on Jebus Cross, especially for the main hero. It is perfectly logical to save movement points by ignoring the rules governing the breaking of ГО on Jebus Cross.

Is there also an option to rewrite a specific rule? Because following the current one, if there were additional guards next to the wyverns, Dark could have done it anyway—so what is the fundamental difference here?

I understand the rule for breaking a double ГО as follows: a player with control can fly or jump to a convenient ГО to break it. HOWEVER, the breaking itself must occur from the player's spawn side, meaning the movement to one of the ГОs can be made via the shortest path using only the territory of their own spawn. In this situation, the break occurs from the treasure zone side, saving approximately 600-700 MP by such an action.