It worked ! I managed to get everything back in place, even after suddenly finding another small rubber thing on my table which after magnifying the pictures here, seemed to have fallen of the motherboard.
So, a part from the fact that this Dragontrail glass is not so strong as promised, I'm really happy I could repair my Fairphone myself.
No "1.6 mm Phillips #000 screw" in my phone
Indeed, the rubber parts didn't came at first, and lastly also the speaker was stuck on the old phone, so this was a rather unwelcome discovery for a non-technician wanting to repair the phone. By lifting it off a small rubber joint came with it so this had to be removed before gluing it back on the new front (a protective adhesive tape needed first to be removed too so this speaker could nicely be glued on. (of course all this is written still without reassembling my phone). Erik