Copper can be solved easily enough by disabling I&F copper ore from worldgen, but silver still needs to be sorted.

I think this is technically on Ice and Fire's side (mostly). Their ores seem to be tagged as "ores" but not specifically copper ore as a copper ore and silver as a silver ore.

A workaround in the meantime would be using a standalone mod that provides ore generation like Thermal Foundation, which Create very much does support. Or you can add the missing recipes manually yourself using Create custom recipes. These are not ideal though.