OK regarding the first picture, yes... it's centered

I have the marquee retainer still in place, but I can guess 10 cm for your arrow number 2 and approx number 1... but just centered it

It also centered on the width, so you should have approx 18,2c m from both side of the speaker
For the second picture,
the middle of the hole is at :
10,5 cm from
the back13 cm from the side
diameter is approx 3 cm
!! your second picture is confusing !! Just rotate it from 180°, and think that the player is in front

Maybe do a picture from the top
