Sorry for my bad English, I'll try to explain it good...
I found the page where Himaruya puts the "humans" names for the Hetalia characters...
It's here (japanese)I noticed that Antonio Fernández Carriedo would be Antonio Hernández Carriedo
アントーニョ・ヘルナンデス・カリエド
...lol! Always was written as Hernández (I say at Pixiv, for example) in japanese, but I think isn't Fernández, because FEliciano and FElix are written with フェ as FE, while Antonio's surname is written ヘ instead of フェ. So, Why did he changed it, if the FE of Fernandez has the same pronunciation as Feliciano and Felix *shrugs*.
Anyway, ヘ sounds like the He in "Hello" (and like "Je" in Spanish), so, and the surname "Jernández" doesn't exist XDDDDD... I don't know why did he messed it so XD. But Heracles also has the ヘ (in my language the H is not pronounced there, so it would be "Eracles") for that I think it should be Hernández (the h is not pronounced, like the spanish version of Heracles)...
And the name of Korea isn't Im Yonsu... it's LI (Lee) YONSU (Yong soo) Wow! ( 韓国:リー・ヨンス )
EDITED: I found at the wikia and it's written
アントーニョ・フェルナンデス・カリエド (Antonio Fernandez Carriedo), I put it at pixiv and appears at "valid" too, with the アントーニョ・ヘ
ルナンデス・カリエド (Antonio Hernandez Carriedo, like Himaruya put in his site)