I don't think the front cover seal them. I use electrical tape over the 4 holes and when the motor is mount on the motor mount, the tape seal it very well.
the front cover works well in general, but it does leave 2 of the 3mm mounting screw holes open the same as any other brushless motor when you mount it using only 2 of the 4 mounting holes. Other than that it completely covers the front of the motor.
I can't decide if its more fun
to make it...
or break it...