Maybe it would be possible, to sort resources available, so that those that are needed to WLTKD are at the top? Honestly that was the only time i had problem with this list not being fit in the screen?
Or add another category like "WLTKD resources Available"? it would usually contain only few lines any way, since often same resources are required for different cities, and some cities are already during WLTKD,
and over all worst case, it would be as much lines as you have cities..
If you hover your cursor over the icon of the required resource, you will see a hint about who you can get this resource from.
I don’t remember where exactly this tooltip appears, check both options:
- under the plaque with the name of the city
- in the extended interface, when the list of cities is on the left side of the screen.
Also, when trading with AI, if you hover over an AI luxury, there will be a hint as to whether this resource is required for any of your cities

But yea, regarding WLTKD there are multiple options.. Some more convenient than other but multiple..