Typing a sentence from the question you got wrong + "NBME" into Google will often bring up a page/forum w/ people discussing it. That will help you get the answer.
No, don't redo UW1. Reading FA1 is too much indirect studying and won't help you. 2CK relies on you having a strong Step 1 foundation, but studying FA1 directly veers from the focus of the 2CK. I'd say the only part of FA1 that's really HY on the 2CK is the congenital immunodeficiency syndromes (e.g., WAS, CGD, etc.). The 2CK somewhat assumes you can Dx a condition but then instead wants the Mx (e.g., you'll get a vignette on lupus, but they want to know the Tx for a flare --> steroids; not just what's the diagnosis). The questions they ask you straight-up for the Dx are usually clinical (eg. tension pneumothorax, aortic rupture, mesenteric ischemia), not basic science-oriented (eg Duchenne), although yeah, obviously you do get the occasional Q like that.
Yeah, MTB2 and MTB3 without obsessing/memorizing Txs can be a good approach. Use any Mx info in those books as mere ideas for how to Tx something (ie. if he lists 3 drugs and 2 different surgeries as Tx, just be aware that they exist as possible Tx, but don't say "oh yeah, I do this first, then this, then this." That will really screw you over if you do that).
I didn't venture into Step 3 questions/assessment. I originally thought about it because I tend to get OCD about stuff / love learning, but I just 1) didn't have time, and 2) it's summer here in Australia, so you try sitting inside without getting ADD.