The first thing you should do after assembling the keyboard is to calibrate the matrix.
You should be able to access ZMK logs through the console. See ZMK docs for details.
Next, you should adjust actuation and release values for each key in the config/tako_drivers/kscan/kscan_gpio_ec.c file. Basically, actuation should happen at the tactile bump, but you can prefer different levels depending on your typing style. If the key actuates too early, then increase the value in the actuation_threshold. If it's too late, then decrease it. After this is done, you should change the release_threshold to reflect the actuation change – reducing it by 50 should work great.
Don't map actuation levels too close to base reads (what you see in console when no touching keys).