Leaks on the front side of the throttle will just mean the turbo has to work a little harder to fill the plenum with the desired boost level, as long as the leaks are not big it wont really make much difference.
Leaks behind the throttle are the ones that can cause you running issues, as they will change the manifold depression if the leaks get bigger or get fixed, so its important to ensure the inlet is air tight before its mapped, then keep it that way and things shouldn't change.


Sometimes compressor housings leaks will cure themselves once the turbo has had a good few heat cycles through it,