Forgive me. I'm not trying to be impolite. I'm not quite sure how you can read that interpretation from the FAQ ruling. Could you please explain how to parse the phrase 'during each attack that round the controlling player must choose to apply the entire effect of Marksmanship or not.' in such a way to suggest that he only gets one crit result over all of those attacks?
You're not being impolite.
Action: When attacking this round, you may change 1 of your Focus results to a Critical Hit result and all your other Focus results to Hit results.
The card text still only allows you to change one focus into a critical that round, not that attack. So by my reading of the FaQ and the card text, you would declare that you are using Marksmanship and your first focus rolled that round (be it the first or the second attack) would become a critical. Then all other focus results that round would become hits.
Hrm... Ok, let's look at it this way, as the FAQ implies.
What is the effect of Marksmanship? Turn the first eye into a crit and the rest into hits. That's the effect of Marksmanship as is clearly stated by the FAQ and the card. The FAQ clearly indicates that, during each attack made during a round, the player must choose to either apply the entire effect of Marksmanship, or not at all. The intent is clearly in such cases that the player may not want to create a crit, such as when using autoblaster or when the enemy has Draw Their Fire.
I can see why you think the way you do. However, I think the reading of the FAQ precludes that notion, due to the key words 'entire effect' in reference to each attack.