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?Impossible to do it unless separate all of them. Tooltip UI vertical is very hardcoded (you can't even change it in the XML file), you just can't add/change more to it.
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 have problem with that, some alternative would be to search for resources using:My screen is too small, the pop up trade overview is cut at the bottom (and some terrain infos as well).
[UI] - Trade Opportunities for VP
TRADE OPPORTUNITIES FOR VP @whoward69's Trade Opportunities mod modified for VP. List of main changes: - all resources (VP, other mods) are reordered (alphabethically) and grouped (by improvement required) with special new header indicating that group; - totally new colours for every detail...
forums.civfanatics.com

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