Every language has confusing pieces like this, which is why context is important. Your example could certainly be confusing, but if even Bob doesn't know who you're referring to, there would likely be confusion in "he helped me out with this problem". It would likely make more sense to say "I talked to Bob. They helped me out with this problem."

Pronouns in any form will make a conversation more confusing if there's no context. If you want to be absolutely clear in your communications, you'd get rid of all pronouns completely. "I talked with Bob. Bob helped me out with this problem. I want to thank Bob for Bob's help. Bob can we talk after this meeting?"

With a definite person it is pretty unusual, yeah.