It's really not wise to make Admissions comparisons of any type among the SAs. Each SA weights different elements of an application differently. This is one of the reasons that some candidates are offered appointments (or even LOAs) from one SA but are turned down by another. Thus, it would not surprise me if USMA (a ground-based service) had tighter requirements for the CFA -- not saying they do, only that it wouldn't surprise me.
USNA does not publish average scores or passing CFA scores. However, those who've been involved in the process for many years tend to have a decent sense of what is "good." It's not set in stone and it's not official policy; rather, it is an opinion born of experience. USNA would say that, until you achieve the max in every event, there is room for improvement. As a practical matter, at some point, certain scores are probably good enough such that the benefits of marginal improvement are outweighed by the downsides of retaking.
For USNA purposes, CFA scores are not viewed in a vacuum; thus, if a candidate is not o/w athletically active, the CFA is the only measure of fitness and will be weighted more heavily. What does that mean? A varsity swimmer who is a district champion will likely be cut some slack for a sub-par (but passing) mile run time as compared to a candidate who has no organized sports. If you're unsure, your BGO is a good source of info. Your RD in USNA Admissions may also have a view.