The point may be moot, as "Cineria" appears to be a stage name, the character's real name being suzuki_ayane (鈴木彩音). Aliases from both cyneria and cineria would probably be appropriate.
FWIW, this wiki gives "Cineria", and the official site is a Flash-laden monstrosity from which no official romanization can be extracted, so I think "Cineria" is probably right.