I know a few guys that have installed similar mounts and none of them have leaked. Mine never leaked. It must not be a prevalent problem.
My first Tee was defective and it leaked down where the flex line went into the Tee. But I returned it and Jerzee sent me a new Tee and line.
One thing when installing pipe thread items like the Tee into the engine block. Mark the position of entry on the first try into the engine and if you can't get the position of the Tee where you want it without risking turning it too tight, then remove it and position it 180 degrees different on the next try going in. (old plumbing trick)