I'm giving my opinion
A dog can be trained, but if as owner you don't train with it, such training doesn't help it. A responsible owner will always train both his dog and himself. And even after training the dog is just a dog and never 100% (well, humans aren't either
), so something like that can happen.
The owner of that dog that attacked yours unfortunately didn't train with it, because if she had, she wouldn't have ever said that your dog caused that incident with its barking.
I'm glad that everything is okay with the pup.
Good night