If country is already chosen, show only the networks from this country in the "Network" list.
I have a userscript for that if you want:
https://openuserjs.org/scripts/gazza911/TVMaze_Shows_Country_Filter
(Just updated that though as I realised it was an out of date version)
Thanks :)
I'm not using it very often, just thought it would be logical. What's the point of allowing user to choose the combination which won't return a single result?