RE: DLE-111 first start... warranty used, but things are looking good.
The way the prop bolts failed , and the way the prop failed, suggest over torque. i didn't hear anything at all odd except for the four stroking as the engine did all it could to stay running when run at too low of an RPM. Engine vibration levels were consistent with an engine running generally right and assembled correctly. An off set crank will just about shake itself off the front of a plane above half throttle, if it managed to run at that high a throttle setting.
I'm not seeing a manufacturer error as the cause.