I too agree. Take this offline until it is concluded.
If still in process, or if a cause has not yet been determined, keep it between the two of you unless an impass is reached and neither party is happy. If that point has been reached, then let's hear all the facts as well as the cause of the problem. I had an
oil use problem with my rebuilt Roush engine a few years ago and even after a complete tear down and evaluation, no smoking gun was found.
Changing your user name is no big deal, but, in this case, APPEARS to be deceptive. Perhaps a qualifier would have been appropriate somewhere in the post.
So, if you want to solve this problem, take it directly to Brent. I have found him to be extremely approachable and he backs his engines completely.
Even Ford requires the customer to return an engine to them if problems arise. Tear it apart yourself, or having it torn down by another mechanic, voids their warranty. If you have chosen not to return the engine to the builder, then you have opened up a can of worms that could be impossible to contain.
Good luck, keep your cool, and let us know what the two of you decide.