Is it a film on the glass or something embedded within it?
Never heard of yellow glass, but I must admit if you've got windows that have lasted that long then I wouldn't touch them and turn the place into a museum! Even our hardwood ones were replaced quite a few years ago, and they were 1970's.
As for making it more modern - I'm wondering if you painted the edges as well in maybe a slightly lighter yellow it might make it blend with the brickwork and perhaps wouldn't look out of place?
Or you could say it's a heat reflective coating a bit like sunglasses for your house. Then wait about 6 months and half the street will have them...! Unless you happen to live in a street where people don't want to keep up with the Jones'. Well, someone has to start these ideas!