Re: 1920's leaded windows
They are not painted!
They dull grey you see is the natural condition of the lead holding the glass together, leave it be. You probably didn't do any damage, but I would not recommend you do that again. If you live in a decent sized town or a town with a number of historical homes there is likely a company that specializes in leaded glass repair/making/installation. Talk to them, they would likely love the chance to replicate your pattern if you like it.
It's this old house, not this built after your dad was born house.