When stationery, both are as hard as far as I can tell.
But CSC5 is stiffer when cornering at high speed.
If want super hard, then go for Pirelli P Zero. Super performance, super noisy.
To be honest, getting a harder tyre to overcome kerb hitting habit is not the solution; the toughest tyre will wear out one day.
To overcome your problem, improve on your estimation skills in tight carparks, especially your usual ones.
Another solution I adopted myself was, the "if not sure, just reverse one more time" rule.....
