A while back there was an announcement from Pega about a know issue with Windows 10 build 1809 and the then-current release of Robotics (I believe 8 SP1). I can no longer find the notification and I'd like to confirm whether there is any known issue with that build and the Robotics versions we use so we may know how to upgrade our systems. Was it Windows 10 itself or with IE in Windows 10?
As of the most current release of 19.1 there are no issues with Windows 10 that I am aware of. The fix for 1089 was added in January and is included in 19.1. I would upgrade as much as possible at one time, to minimize the amount of testing that you need to do. In terms of testing the upgrade though, I would take one machine and run your current code on the new Windows 10 build and ensure it works. Afterwards, I would update the code and then update Runtime to the 19.1 version and run it again to ensure that it continues to work.