Is quality of VGA Horizontal and Vertical sync Pulse relevant to be able to display on sensitive projectors
Overshoot or delay are not the cause of the problem. Overshoot should not be more than 30% of the logical pulse. Here, we don't see the exact measure but it is no more than 24 %.

As for the delay, it should not be that large, but internal loops in the design make it that way. However, it doesn't prevent the display to work.

What was causing the problem was color levels being 1V instead of 0.7 V (R, G, B) pins.