Front to back, not transverse. Only talking sections here so strictly 2D. A negative Cp means pressure below ambient pressure. When such a negative pressure peak gets near the water surface, it causes the surface to deform and when the deformation is big enough the foil sucks air and down you go without even getting a tip out.
Here is a NACA 0012 at 10 degree AoA to show what I mean:
Huge negative Cp spike right near the leading edge, falling quickly and then more gently down to zero. That nice gentle slope from 20% chord aft means a very gentle pressure recovery back up to ambient pressure, and thus a modest adverse pressure gradient (going from low pressure to high pressure as we proceed from leading edge to trailing edge on the upper/suction side of the foil surface). With a modest adverse pressure gradient, risk of stall (trailing edge stall to be precise) is low and it will be very gentle and progress slowly and predictably when it occurs. But, if that pressure peak comes anywhere near the free surface it will suck air suddenly and violently lose lift.
Contrast that with the first image you posted (forget the differences in angle of attack for now).
The suction pressure peak is much more modest near the leading edge and the pressure coefficent stays at something like 70% of the peak value all the way aft to 50% of the chord length. For the same lift coefficient (area under the Cp curve) as the 0012 section above, this more spread out pressure distribution will be able to get much closer to the free surface before it ventilates and the ventilation won’t be nearly as violent, giving better chances of recovering from it without crashing. But, look at the slope in the pressure coefficient from about 55% to 75% of chord - very steep, meaning a very strong adverse pressure gradient, and much bigger risk of stall - more violent, sudden, and unpredictable stall affecting the last 30-40% of chord all at once. This is the fundamental challenge with these types of so called roof-top pressure distributions (ones that avoid big peaks and stay high over more of of the chord length) in general, and foil reflex in particular.