I trained the raccoons that visit my house at night. I started them out getting a peanuts from a water bottle. Then I tied the bottle to a rope. Then kept raising the bottle higher. At that point, I built an automated feeder system using a linear actuator activated by pulling the rope with the bottle attached. It had LEDs that were green / red to show when the feeder would / wouldn't dispense peanuts. It was all driven by an ESP32, it even had a web page on our LAN reporting how many correct / incorrect pulls were done. Over the coarse of a few nights they figured it out. Raccoons are so cool.
Man, I'd have trained them to put coins in a little hopper for the food. Start by leaving the coins on a string similar to how you did it. Then set it up so pulling on the string drops the string+coin into the hopper, triggering the food. Then leave coins on the ground near the hopper. Then... start leaving fewer coins around. Soon, an army of racoons will be bringing you street coins in exchange for peanuts.
One feeder for racoons, and another for crows! Then over time you scale it up by having feeders with cheap snacks and feeders with expensive snacks. Then have a leaderboard to see which animal brings in the most money!