The sthala puranams find mention in Thevaram itself and there are multiple temples with the same sthala puranams.
For eg - Lord vishnu did archana with 1008 lotuses to Siva and finally found one short. He plucked his eye and offered that as the 1008th Lotus. This story is refered in 2 temples. Thirumarperu near kanchi and Thiruveezhimizhalai near Mayavaram. Both have the same Puranamas and Thevaram refers that in both temples.
The Namakkal cave temples. Though there are puranams associated with it, we know that as per epigraphs it was built by Adiyaman King Gunaseela. If we have not recorded the epigraph - Gunaseela will never be known. There is a famous Vishnu temple near Trichy by name Gunaseelam.The sthalapuranam mentions about a rishi Gunaseela, who made the lord of Tirumala to come there. Usual sthala puranam - cows emptying milk etc etc..... http://en.wikipedia.org/wiki/Gunaseelam_Vishnu_Temple a. The Gunaseelam - May be a temple built by same king Gunaseelab. During the 60 year closure of many temples and mayhem - many would have left the placec. After the return, after the late discovery of the temple - the story might have been wrote.This may be a case or may not be - we dont know.But there was a Adiya king by name Gunaseela, who built two cave temples for Lord Vishnu in Namakkal. In the Ranaganatha cave, he had mentioned the name of all Murtis - Vishnu, Brahma, Isa, Brihaspati, Sukra, .....Rest i leave it to your opinion.