I can't see the image of the tank so I am going to talk in general...
Kuhlis and corys are perfectly fine together and won't outcompete each other. The kuhlis are skittish fish, they'll hide a lot but in a heavily planted bottom they come out for food together with the rest of the fish. There are surely areas where other fish can't get to the food?...I kept mine for a long time in crypt overgrown tank and there's no way a larger fish could easily get to the food at the bottom.....
Maybe try not to drop food just in the open areas, make sure some sinks amongst plant roots and the kuhlis will get to it. They would love some caves. All of mine occupy coconut caves. When I had two caves, they had divided them between themselves. Then I moved them to a smaller tank, with just one cave, they all went into one cave. When I quarantined a small clown loach with them, the clown loach too went into their cave

They'd be very brave eating around their cave.....You'd see them poking their noses out immediately after food is dropped. So dropping food near that cave or inside it even will ensure they get some food but I am pretty certain they'll manage find it anywhere there's left overs. Although not exactly nocturnal, they'll come when the lights are off if they are intimidated by other fish..I moved mine to a larger tank that has grown clown loaches in it and is not so planted and I noticed them being out an hour or two after the lights have turned off when the clown loaches go to sleep... They used to be out during light hours when they lived in a heavily planted tank with corys. They do love sand bottom. They sift through it constantly....more important to them than even corydoras so if you have any sort of gravel, that is any bit sharp, I wouldn't get the kuhlis...They wiggle through the sand when they move....I am not sure how it will work out without sand bottom for such a fish..
Alternatively, they do really well in a sand tank, the bottom being covered with leaves....They'd be amongst the leaves constantly...Other than that, they are really hardy fish.
Good luck.