Well, first off...Those are 2 fine looking brown coturnix hens you have there!
Next, as long as your garage is between 33 and 99 deg. F., then temp is not really a problem. Coturnix lay like banshees in a temp. range between 40 and 60 deg. F..
Light...well I do recommend 14+ hours of artificial light if raised indoors, but any amount of natural sunlight trumps artificial light. It's ok to provide low intensity full spectrum white light 24/7 ( a 4.5 watt night light).
I guess this is #3, but a good diet is always a plus. Short of that, a SAME diet is best. Don't throw everything but the kitchen sink at them. Just give the the sameness they love. What ever you are feeding them, keep it up. They shutter at the sight of a Japanese bar, when someone is just cooking up and throwing flaming eatable things their way. Same feed, clean water, a dust pan...Just fine! Perpetual sameness.
#4, Don't handle them to much. I'm not sure if you do this, but over handling coturnix can cause that egg to slip past the egg shell and paint department and become a shell less egg. Forever lost between the wire, or in the litter.
I can't resist the bean counter in me. When your 2 girls start laying, you will get (ABOUT) 2 eggs a day. It will take them about 7 days at 99.5% production to net you a 2 (Large chicken) egg omelet. It will be the tastiest omelet you have ever eaten.
I'm thinking you need some more hens too. 4 solved my hen egg addiction, so 3-5 per person can keep one from running to the store for eggs. Just my best guess.