No bolts are fine the just do NOT SLIDE INTO THE NIPPLE Unable to tighten tight enough.
This is Kohler specific. It has 3 mount holes instead of 2. The seal is not as thick either.
The tank to bowl gasket maybe worn. I would first make sure that all 3 nuts are snuggly tightened.
Tighten the bolts and check the level side to side and front to back
I think that is a different system for the valve in the tank. This is the gasket that goes between the tank and the bowl.
There was a plastic gasket that went between the rubber gasket and the nut that holds it and the canister assembly to the tank.
IT MIGHT THE PROPER ONE BUT IT DOES NOT SLIDE INTO THE NIPPLE ONCE YOU THREAD IT THROUGH THE TOILET. I thought I was nuts, used all the comments written by others, but we could not get them in tight enough to tighten enough for a seal. I slid them into the nipple before putting in the tank bottom and the went in smoothly. Put the nipple through the base of the tank and THE BLACK TOP PART OF THE BOLT WILL NOT GO THROUGH......
OK this is what I did on mine and it fixed it. My tank is not perfectly flat on the bottom. It actually curves up into the tank area so the tank to bowl ring gasket would not seat properly. I took a razor blade and cut down the three rubber spacers at the bolt locations that sit between the bowl and the tank. Cutoff about 1/8” of rubber each and boom! Now at seats and does not leak.
I have a K4620 and it worked. I talked with the guy at Home Depot and he said it is universal for Kohler 2-piece toilets. Note that the bolts shown on the website are not the bolts that actually come in the kit. Not to worry, the bolts in the kit work. You may think they are too short, but they aren't. Check some of the answers regarding how to install the bolts that may, at first,seem too short.