The patch notes mentioned removing Ancient Iron Coins from "the above monster zones" listed, but did they drop anywhere besides those zones? 

Were they removed from the game completely or could I still get some if I went to, say, Kuit Island?

Yeah, I used that coupon and since I knew the core was for bartali log I assumed the coins would be for Deve's, both of which I've had done for a long while, and promptly sold them to the nearest Trade Manager. 

The end of valencia 2 had completely slipped my mind for the coins.

Thanks for the info about upcoming fix news though, I hadn't seen that and as long as the King will eventually give the 2 coins for Afaru and the other dude I can put off finishing / accepting that reward until they do.

I don't see Padix island listed as being a patched area so you should be able to loot anciens coins there.