Been there, done that, I once used similar lights, although not in the
kitchen.

Chuck the lights. Even if you manage to get them mounted securely, the
"pucks" will yellow and crack within 6 months.

When the bulbs burn out, and you twist the cover off to replace them,
the cover will split/crack; assuming it hasn't already fallen off
anyway.

Finally, these things radiate WAY too much heat out the back; they are
a fire waiting to happen.