Can I ask some rationale from whoever submitted the tag change from Eruru/Aruru to Eruruw/Aruruw? ANN (which I'd like to remind everyone is user-editable) is split on the issue, and the 'official' spelling (http://aquaplus.jp/uta/characters.html) is エルルゥ (Eruruu) and アルルゥ (Aruruu).
I've heard an 'Ainu spelling' argument (suggesting that Utawarerumono is inspired by the Ainu culture), but reading over the wiki page on the Ainu language (http://en.wikipedia.org/wiki/Ainu_language -- yes, it's also user-editable, but with stricter verification and sourcing standards than ANN) I see no special case which would suggest the use of w for ウ or ゥ using either the katakana or roman typography, so I can't see where this would follow there either.
So, this said, I'd like to propose a change: either restore the previous eruru/aruru (yes, I know it's available as an alias but I think the relationship is backward in this case), or set the tags as eruruu/aruruu, with aliases all around. I'd personally prefer the latter case as it follows with the trend of giving consideration to correct romanization.
Resources:
Utawarerumono homepage: http://aquaplus.jp/uta/
Ainu language: http://en.wikipedia.org/Ainu_language
Hepburn/MH/RH romanization: http://en.wikipedia.org/Hepburn_romanization
Edit: fixed broken parentheses.
Updated by accRei