So should we judge the teachers based on how they tried to make decisions in the moment when the author was young, or should we judge them based on the results of their decisions with the knowledge that we have now? I find that quite a hard question to answer definitively, but I do know that I tend to use the former rule for myself and the latter rule for others, which certainly seems quite unfair to me.
The question of "guilt" or "judgement" is more complicated, as you say. Where many people go wrong is that they automatically jump from harm + responsibility towards guilt. That's how you end up with articles like these where the author feels like he has to choose between anger towards his teachers and thanking them because they tried their best. That's a false dichotomy if I have ever seen one.
A teacher who traumatizes a child isn't that different from a surgeon who botches a surgery. It doesn't mean the surgeon is a terrible person but neither does it mean you have to be thankful to the surgeon because he tried and because he operated successfully on other people.
