Kingsbridge Scarlet: trade 1 cloth for 3 VP

Question

In Chapter 4 long-term (blue) event card, there's one that says:

Each player may trade 1 cloth for 3 VP

If this were a one-time card, there wouldn't be any issues. However, as this is a blue permanent card, there might be different ways to interpret this text.

1. You can do this once in Chapter IV, does not matter when.
2. You can do this once per turn, may be at a specified time, such as after an event card is placed, and before the personal income is resolved (i.e., at the time when the grey one-time cards are usually resolved)
3. You can do this as many times as you want on your turn.

Well, Option 1 is not really compatible with the concept of a permanent card, and tracking who used it, and who has not, is difficult. Options 2 and 3 seem to give too much to the player who happened to have the wool and/or cloth in Chapter 4: otherwise, one cloth would be worth 2 points if you sell it for money, the second cloth would be worth 2 points if you played "Privilege" to sell it, as well, and others would not be worth anything. One of the players managed to get 12 or 15 points with this card though in our recent game (although she still lost to a powerful project builder); we played it as Option 2. I was unprepared enough to discard my "Cloth production" in the first turn of Chapter 4 before this blue card appeared.

Are there any official explanations for this card? What are the existing house rules for this card? One possible way to mitigate its power is to say that you can trade cloth for VP in place of your action, for instance -- nothing except for "Build project" can give you 3 VP at once, and one, obviously, is not allowed to play it four or five times in a row.

Answer 1

I cannot find an authoritative source, but according to my best reading of the rules and BGG's forums, you can make the trade once per turn, during the phase of your turn when you play your action card, as long as that event is in play.

My justification:

1. p. 7 of the rulebook indicates that "for long-term events, you may make the trade once per round."

2. p. 3 indicates that blue event cards must be taken into account when playing your action card.

Together, I take these to mean that you can only make the trade once, but that you can make it every turn, and around the time of your turn when you are using your action card.

These threads on BGG suggest the same thing. One of the posters cites an official Mayfair answer, but it's not linked anywhere.