Having just returned from Croatia I noticed this thread, and as is mentioned in the OP I was a member of the committee. While I prefer not to go into our discussions I can give some additional facts (and even a personal opinion about the level of the declarer...).
The level in Pula is quite varied, I would describe the actual declarer as decent but not close to being considered for playing for his country (we played against a couple of considerably stronger polish teams).
The declarer hardly spoke a word of english. The way the case was presented to us he showed his hand without saying anything, pulled it back up and then said something in polish which his partner translated to "He believed his club J was the K" (not sure how long each step took and the OP is probably correct that the last step was after the TD had arrived). I am not sure when the TD asked if he noticed Wests discards and whether he also noticed the diamond-discard (in our defence we were short on time and 20 minutes into the next round when we finished, but we could have asked more questions...).
In the committee a polish TD translated, and here they disputed that a claim had been made (which I think was not mentioned to the TD at the table). They did not bring any new facts to back this up.
When asked (via the polish TD) about which 12 tricks he had with the club K and how he knew the club had been discarded from 4 the answers were not very convincing. He said he knew from the bidding (even if E/W had passed all the way...) that West had been squeezed...
In the final ruling we allowed declarer to take the clubfinesse, but did not let him get his club 2 as his last trick. Instead we assumed he would play for a failing double-squeeze. I do not remember the details, but Jan wrote down a scenario where he would be stuck in dummy with a non-high heart T as his last card (I must admit that I am not able to reconstruct the exact line now, but it assumed that East, with a presumed club-stopper, discarded his potential heart-stopper on the diamonds...).
John