Awww I'm sorry you are loosing keats. I don't think the lamo should have been an issue if they were able to move out from under it. Though I don't no how your set up is. Is it solid where the whole thing would have gotten to hot and it not matter if they moved? As far as potatoe I'm not sure on that 1. I never tried giving mine stuff like that. They really don't show much intrest in veggies and stuff.
They were in my quarantine cage because the rest of the chicks were too interested in eating their beautiful orange toes. Quarantine is a 10 gallon aquarium (small) with a mesh lid. Heat source is a ceramic bulb on one side of the aquarium so it does hold in heat really well, which is good because it's really close to the AC. Directly under the heat lamp it was about 100F which I know is too warm (was working on getting another ecoglow brooder for them) but the rest of the aquarium was a comfy 90F give or take a few degrees.
They could move away from it but when I turn of the ottlights for the night, they can no longer see so they just sleep (which is great for MY sleep plus they are in a day/night cycle) but if it was still too hot where they were and they couldn't see to move away... I don't know.

I give my chickens vegetable scraps like that all the time, but I've never given it to baby guineas so I didn't know if they have some intolerances that I didn't know about.