I think the main culprit here is the English Wikipedia page of Hikashu (the music collective Sakaide belonged to).
I already linked to the Hikashu offical page in my previous post, but it clearly says さかいでまさみ there. The Japanse Wikipedia page for the band has the same transcription, but the English page transcribes his name as "Masaumi Sakaide" instead. I got zero hits searching for the kana rendition of that in Japanese pages. The same goes for the other variants.
Assuming this page:
http://www.amrta.co.jp/event/04_3_30.htm is correct this info seems pretty solid to me.
I didn't find any other authoritive English sites that mention one of the variant names. There's always the possibility there was a misprint (or misprints) on one of the actual abums he contributed to though.