GNU COBOL works fine on win10 on my system. I didn't trye all the features but a first try worked nice and was also fast.
MicroFocus is ok when you can afford the costs.
When you work with a prompt and an older COBOL, you need probably to set the legacy setting of the CMD prompt to on. CA Realia works also with this setting. Without the setting, it is incredibly slow. A program to get an idea of the speed, uses 0.04 seconds. Whithout the legacy setting, it takes several minutes.
I never understand Microsoft with these things. It does not feel ok. It feels like sabotage.
Also talking about legacy is in fact not nice at all, certainly when you can still use your work from 30 years ago. One should talk about Return On Investment = ROI.
Buy a car. Will it work after 30 years? Probably not. Your COBOL program probably will. That is the big difference.
It is not so honest to discourage people to enjoy their ROI.
Have fun!