Scenario is as follows.
We have an option to purchase source code for a Swift-based application, make changes to it and then recompile for Android. I have found https://www.remobjects.com/elements/silver/ which runs on Windows.
Is it possible to open the existing source in Silver and then do as described above, or would I need to use the specific tooling used by the original developer?
You'll have to make a lot of changes to it, just to get it running on Android. The language you use is independent from the platform. You could probably reuse the business logic, but certainly not the GUI.