Well.... :)
Thinking that the transfer paper was old (as mine was one of the first issued kits) I decided to scan the PlayStation logo and print it on a brand new transfer paper.
And I ironed again... for two hours !! :)
Largest mesh: I managed to get the logo on it but extremely faint.
The 2 small meshes: nothing.
I then decided to paint the 2 small meshes following the pattern underneath... ahaha... HUGE mess as even with a black / white primer the paint would not really stick to the mesh: it went both on top and thru the mesh.
I gave up. I will still have an okay logo display concerning the large mesh and just two regular meshes at the front.
I should have known that ironing isn't my thing anyway :) :)