The facts I'm presenting here may not be 100% what actually happened at the table, I didn't check the "things opponents should know about" section of their convention card although Bluejak did, but suppose for the purposes of discussion that the facts are as I describe. Assume there's nothing in the "things opponents should know" section but the cue bid is correctly described in the section relating to it. No screens in use, EBU has no pre-alerts.
All vul, dealer W who passes. N opens 1♣ in the context of a weak no trump system that means that this is at least 4 clubs, and unless the hand has 15+ points, will only be 4 cards if exactly 4414, otherwise 5+.
E overcalls 2♣ described by W on enquiry from S as "weak takeout double".
S doesn't ask further but thinks that he hasn't a clue what 2N and X mean in this undiscussed auction, has sort of come across this before where you do one thing with an 11-14/15 ToX and something else with a 15/16+. He reckons that if there's a trump stack then it will be onside, the K♠ is odds on to be in the hole if partner doesn't have it so he bids 5♣.
It turns out that this "weak takeout double" is 6-11 (or more like 8-11 vulnerable) and the spade finesse is losing, 5♣ is basically on the finesse and it fails by one for a poor score. S is unhappy in that if he got a better explanation (which although correct was incomplete), the spade finesse becomes 50:50 rather than 65:35 and he wouldn't have bid 5♣, although it's not clear what he would have done (possibly 4♣ over which partner may or may not bid 5).
Is S ruled to have damaged himself by not asking further/checking the card, or is he entitled to some remedy ? Should EW have put this in the "things opps should know" section of the card, and if so, are they liable to any sanction for this ?