User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-7264921-20130926121058/@comment-7264921-20130927213332

Japanese IME uses a non-standard romanization, which is a combination of the three standard systems (Nihon-Shiki, Kunrei-Shiki and Hepburn) and added commands like "dhu" for デュ and "lyu" or "xyu" for ュ.

Again, "dhu" is not the correct romanization for デュ in any of the standard systems, but only a shortcut for the IME. If "Amadhura" is an acceptable romanization based only on the IME system, then so is "Amadelyura" and "Amadexyura". Please note that none of these is true to the original Japanese name in terms of pronunciation.

"Amadyura", however, is the correct romanization in the three systems, and is consitent in pronunciation.

And about people using the wiki as a reference to typing, I don't think they actually need the non-standard transliteration for that. Mainly because someone using a Japanese IME, more often then not, need to know at least the basics of kana, and are able to interpret a word like アマデュラ as "a + ma + de + little yu + ra".