http://ponniyinselvan.in/forum/history-discussions/thiruparamkundram-non-muruga-temple-3209.html Based on this topic, it has been assumed that the temple was originally a jyestha devi temple. I was very much fascinated by this temple during my last weekend visit. The amazing statues 8 handed(thats what I could make it, it could be more) ganesha, varahi feeding her piglets, rani mangamma, thirumalai nayakkar, etc are astounding.
Thiruvachi(not sure if I got it right?) around the murugan karuvarai has the european angels around, probably a later day addition.
What if the other dieties are a later day addition just like what the inscription says? Why cannot be the Murugan sculpture be the earliest among them? This temple has lots of inscriptions, probably a feast for Chandra if he went to copy them.