It's impossible to really discuss this meaningfully without details. However, errors are still errors, and ATF seems to have no sense of humor about such things.
And since we don't know how frequent, numerous or serious those errors were, how can we even intelligently discuss whether revocation of the license was too extreme a penalty?
"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