Based on the new information it does seem that the errors were minimal, unintentional and innocuous. So this appears to be another example of ATF being unduly harsh. Unfortunately, not the first time.
"It is long been a principle of ours that one is no more armed because he has possession of a firearm than he is a musician because he owns a piano. There is no point in having a gun if you are not capable of using it skillfully." -- Jeff Cooper