Typically, any lyrics that aren't in the original version are put in a separate table. Putting them in the main lyric table is certainly a no-go.
Personally, I'd like to have transcriptions of those parts on the wiki, even if there's a chance they're incorrect, but... well, someone who actually knows Japanese would have to do it. A romaji transcription wouldn't be terribly helpful.
(Some parts might already be transcribed, though, such as Chihaya's solo inferno dialogue.)