So on Natalie Imbruglia's 2009 album Come to Life, there are 4 Coldplay-related tracks - Lukas, Fun, Scars and Want. Lukas and Fun were written by the band themselves. They also played the instruments (with strings by David Rossi), which leads me to believe that they're the instrumentals from the songs Coldplay would have released themselves. Lukas is produced by Brian Eno, Markus Dravs and Rik Simpson (obviously evidence the song was from the Viva la Vida era). Fun was produced by Ken Nelson with additional production from Rik Simpson (this is what makes me think the song was from the X&Y era at the latest, as the band has not worked with Ken Nelson since). Neither Ken Nelson nor Brian Eno produced any other songs on Come to Life.