Yes, Laddinfance is an official Arcane Wonders response and settles the debate. I actually discussed this with him at GenCon. The official answer is that both distances are equally valid and you can choose either zone when measuring. The result is that a range 1 attack can hit a wall bordering the attacker's zone.
Also, in case it needs said, it is official that distance is a separate measurement from Line of Sight. So the fact that you don't have line of sight to the zone on the far side of the wall, does not prevent you from measuring distance to that zone. You still have Line of Sight to the Wall itself, and your choice of zones for approximating distance to the wall is valid.
We have a new case since this ruling was handed down that I discovered in recent play this weekend. I wanted to check our interpretation of the Attack spell Luminous Blast. It is a Holy, Light Ranged Attack with Min-Max range of 0-0.
We played that this 5 dice spell could attack Walls in the adjacent zone border, which proved a very effective method to help take down walls. However, on reflection after the game I discovered this discussion folder and the following statement on p.14 of the Rules Supplement.
"Zone borders are not considered to be inside the zones they border, so a Zone attack will not affect walls."
Before Luminous Blast was released the only Ranged Attacks that had a range of 0-0 were Zone attacks that targeted a Zone. So the question is does the quoted statement above apply to ANY Ranged Attack with a 0-0 range or just to Ranged Attacks that Target a Zone and use the Zone Attack icon?
Did we play Luminous Blast correctly?