They are 5 months old. They may have already finished their juvenile molt, may not have. You will soon find out.
Some chickens skip the molt their first fall/winter but some do not. Again, you will find out what happens with yours.
If an entire feather is removed it will soon grow back. But if just a small part of the shaft remains it will not grow back until their next molt. So yours should remain until they molt. You trimmed them, you did not pull them out.
I don't know how cold it gets in your part of California but I would not worry about them getting cold. What traps tiny bits of air for insulation is their down and really fine parts of their feathers. You should not have removed enough of the feathers to affect that.
I do not think you have anything to worry about as far as the cold by clipping the feathers like that. Good luck!
