I don't see anywhere that Gepard ammunition has proximity fuzes. And I'm not sure a proximity fuze would work very well on a glide bomb. Proximity fuzes were introduced on large caliber AA gun ammunition in late WW II. The US Navy was the primary user, though the Army got some too. The shell has a simple radar in it that when it gets near a target it goes off. Before then fuzes had to be set assuming the distance to the target and the flight time. Misjudge the distance and the shell will explode too far away from the target to be effective.
Short range gun AA is usually auto-cannons that fire a burst at the plane in the hopes of getting a direct contact with a shell. The Gepard's 35mm shell will do significant damage to any aircraft if it scores a hit.
The problem with shooting down a glide bomb is that unlike an aircraft, it's got a steel casing and it's much smaller than an aircraft. It's traveling about the same speed range as many drones, but it's only in the air a relatively short time after release. Any kind of AA needs to lock onto the bomb and launch in time to intercept the bomb before it hits its target. It's a very difficult problem to solve.
Some glide bombs are laser guided, but it requires someone to keep a laser on the target until the bomb hits. This is useful in close support where an infantry unit on the ground can keep the laser on target and the plane can escape. Otherwise the plane needs to linger until the bomb hits with the laser pointer on the target. I believe this is the old guidance system Russian aircraft used before the war. When they had smart bombs, but they used up most of them in Syria.
The other option is a GPS guided bomb which is drop and forget. Either the bomb is pre-programmed on the ground before take off, or it's programmed by the pilot before dropping. GPS guided bombs have the disadvantage that if the enemy is using GPS jamming, the bomb can get confused and not know where it's going. More sophisticated GPS guided bombs have backup systems that it will try to figure out and hit the target anyway if the GPS signal is jammed, but I doubt the Russian glide bombs being employed now have much sophistication.