I think it's worth distinguishing between "underconfidence" and "lack of confidence" - the former implies the latter (although not absolutely), but under some circumstances you are justified in questioning your competence. Either way, it sounds like you're working on both ends of that balance, which is good.

Though part of me is still worried about making SIAI look bad. And I'm still worried that the stuff I've already posted may end up harming SIAI's mission (and my mission) more than it could possibly have helped. Though of course it would be a bad idea to try to hide problems that need to be examined and dealt with. And the idea of deliberately trying to hide information just feels wrong. It feels like Dark Arts. I should also mention that the idea of deliberately not saying things, in order to avoid making the group look bad, isn't actually something I was told by anyone from SIAI, I think it was a bad habit I brought with me from christianity.

I think this is good thinking.