Terms was a way that Canonical negotiated with others that “they have to agree to legal terms”, but they don’t have to necessarily block on an install screen to do so. The idea is that you can register a set of terms with Canonical, and then we will track what users have agreed to what terms, and when they go to deploy software that requires terms to be agreed, we can confirm if that person has/hasn’t agreed.
It doesn’t handle the GUI pop-up, and generally needs legal people to meet, since one bit of software was released that says “you must agree to terms” and you need to get the people offering that software to be ok with those terms being agreed upon in a different way. (It was modeled after Java terms for things like Oracle’s JVM.)
Given limitations there, I would probably say you need something more along the lines of having the charm set a Blocked status, indicating the user has to do something manual in order to proceed. If you can put that step into an Action, all the better, but it sounds like the actual steps are around getting a GUI in front of the user. Which is always a bit muddy in a cloud world.
Given that you’re running a Windows application, I would probably look at trying to get RDP working. You could use an action to tell the user the details of how to connect, and set that in your Blocked message.