Protocol Droid said:

Obi-Wan: I took it upon myself to train him as a Jedi. I thought that I could instruct him just as well as Yoda. I was wrong.

That does not address the 'Did Yoda train Obi-Wan or not' topic. It just means that at one time Obi-Wan considered himself as good a trainer as Yoda.

But why compare himself to someone who only had a limited role in his training? Obi-wan comparing his training abilities to those of Yoda suggests a lot of first-hand experience being instructed by Yoda.