The problem is with the modern ones. They are now very poorly made and the cost of repair can equal the cost of a new clock. As a general rule a stained and polished cuckoo clock will usually be an old one. When they started painting them in bright colours their merit becomes questionable. Date and Moon Work.
Many old clocks feature a simple date, and often moon phase indicator.
Most of them don't work, even after a so-called restoration. True there are some old clocks where the datework was never finished to work, but these are the exception rather than the rule. If your clock has a moon dial you can set it here. I repair the movements of aneroid barometers and have a chamber for testing and calibrating them. I service and repair mercury wheel and stick barometers, I can get custom-made tubes for thermometers as well as the barometer main tubes.