So you're not getting a message box after you equip a power or metal armor? If it's not already try loading Impervious Power Armor.esm after FWE's .esm.
Maybe try opening the console and typing the following "
Set ImperviousThreshold to 1". This will make the mod work more like the DT system in the originals an NV. It might jump-start the mod if isn't working. Also it's suggested in the ReadMe that if you're using FWE you need to increase the impervious multiplier. You can do this by typing in the console, "
Set ImperviousMult to 2.1"
I don't know, I've never had a problem with using IPA and FWE together.