Hi,
well that needs to change imho 
If you look at pretty much any other 3D package there’s no UI requirement to have an active viewport to use a viewport shortcut, it just works!
I ran in to this issue a lot where I was continually cutting by box then loading back the reconstruction box (I reported this a bug with the box disappearing after the cut), I want to quickly switch viewports to align the box where I need it. It’s very hard to replicate otherwise I would have screen recorded it but I’d say about 75% of the time I have to quickly click back and forth to reactivate the viewport to get the shortcut to actually work. Perhaps also cut by box is switching viewports after use?
It’s very flaky as a UI because a shortcut should be exactly that, rather than click back and forth it should activate current 3d viewport as part of the shortcut. Anyway no worries if its too hard to do because of code legacy etc.