Facts in evidence:
1. EBU jurisdiction (it's in the title bar).
2. The NS agreement wrt the double is that it shows diamonds.
3. South doubled "to muddy the waters". (It's unclear whether this is actually a fact, or just the opinion of the OP). (Post #21)
4. The director ruled "that E/W had been damaged and did some silly 12 C ruling giving x % of 1NT 90 y% of 1NT 120 z% of 1NT 150". (Post #45).
The OP asked "your ruling?" (it's in the title of the topic). We have an ongoing argument, but we don't seem to have consensus on the question. The simple answer to this question is "there is (as of the original post) insufficient data to make a ruling". Somebody did say that, somewhere on page two, I think.
Four pages of discussion on a simple ruling? Ridiculous. Also, it should not take 45 posts to extract from the original poster pertinent facts about the case. I'm tempted to split the topic, and move all the back-and-forth jabbering to a new topic in "Laws and Rulings", but for the moment at least I'll leave it all here.
The discussion has revolved around whether North had unauthorized information from South's failure to ask a question, and whether South illegally attempted to communicate with North by not asking. As I understand EBU regulations, there can be only one meaning of a call that does not require an alert. If an alert is made, then, the only thing opponents are entitled to infer is that the call does not have the meaning that does not require an alert. In this case, that means that the alert of 1
♦ conveys that the bid is not natural. NS have the agreement that a double of an artificial (i.e., not natural) bid shows the suit bid. So South's double shows diamonds. South doesn't have diamonds. Did he psych? A psych is a deliberate and gross distortion of high card strength or suit length. It seems to me south call grossly distorts his diamond length. Was it deliberate? Yes, point 3 above so indicates (assuming it is a fact). So until we find out that point 3 is opinion rather than fact, we base any ruling on the derived fact that south psyched. Is this legal? In general yes (White Book 1.4.1, last paragraph).
Was south illegally attempting to communicate with North (Law 73B1)? I see no evidence of that. So he didn't ask. That's not evidence of a violation of 73B1. If it's evidence of anything it's that he knew from the alert that East wasn't showing diamonds.
Did the fact that south didn't ask convey UI to north? I don't buy it. Everybody at the table should have been able to infer that East wasn't showing diamonds from the fact of the alert.
So it appears that there was no infraction. That suggests the table ruling was incorrect. Aside from that "Damage exists when, because of an infraction, an innocent side obtains a table result less favorable than would have been the expectation had the infraction not occurred – but see C1{b} below." (Law 12B1). 12C1{b} says "If, subsequent to the irregularity, the non-offending side has contributed to its own damage by a serious error (unrelated to the infraction) or by a wild or gambling action, it does not receive relief in the adjustment for such part of the damage as is self-inflicted. The offending side should be awarded the score that it would have been allotted as the consequence of its infraction only." The argument here is that EW would have got to some number of NT absent the double. Personally, I doubt that. I suspect that absent the double EW would have bid exactly as they did with it. So even if there was an infraction, there was no damage.
The thorny question "how do you minimize the potential for UI when the opponents alert a call?" would be better served with its own topic — in the laws and rulings forum.