One possible reading of the first part is "Nene" which makes sense given the "ねねろぐ" at the top of the site ("Nene's Log", I assume). As for the 葉, I'm getting 5 potential name readings (Shou, Tsuruba, Haruka, Midori, You). In this case, where there's nothing on the site to give a clue... honestly, just pick the one you want. Then what I do is put "Name reading is best guess." in the comment for the artist entry.
I'd probably go nene_you since 'you' is one of the readings of the kanji itself ::shrugs::
葉月 said: Neneyou would sound pretty strange. Neneha is much more likely.
Are we sure it's a single name or a full name? 音々 葉 (nene_you or whatever) or 音々葉 (neneha or whatever)
Since it's unconfirmed, it'll probably be best to stick with royalcotton.
Not necessarily, artists get tagged with best guess names all the time. That's accepted. But since there is already a tag in place, I'm fine with leaving royalcotton as well.