As we think about the legacy of the EWF in the late Third Age, we first need to remember that none of the humans of Dragon Pass are their heirs. All of human civilisation in Dragon Pass was destroyed in 1120.
But the EWF left other peoples, ideas, cults, and other monuments in their wake. These include such peoples as the ducks, other Beast Men, the tusk riders, and the Puppeteers. Auld Wyrmish remains as a written language. The Big Rubble, Praxian Sun Dome, and Six Sisters are monuments to their power and skill, as are many smaller monuments and ruins. And even the Orlanth Rex cult can be understood as a response to the EWF.
And of course Delecti and Fang Forash are both survivors of that era. Delecti’s undead army no doubt had it prototypes in the decadent late years of the EWF.