Can there really be rule ambiguities in a co-op game?

Maybe it’s the role player in me, but: make a ruling and move on. Be consistent with your rulings, right up to point where you decide it isn’t working the way you want and then make a different ruling.

I don’t know that would even occur to me to consult a faq for a co-op. Which is probably why we have a good 100+ games of 1e in, and never encountered a single issue, or at least none that took long enough to resolve-by-ruling that it rose to the level of issue.