Manipravalam was a literary style used in medieval liturgical texts in South India, which used an admixture of Tamil (early Malayalam of Kerala) and Sanskrit. Manipravalam is termed a mixture of Sanskrit and Tamil. Tamil language was the language of the region, part of Tamilakam, at the time of Manipravalam's genesis and use and its introduction caused a significant transition of Malayalam from Tamil in Kerala. Mani-pravalam literally means ruby-coral, where Mani means ruby in Tamil while Pravalam means Coral in Sanskrit. Malayalam is referred to as ruby and Sanskrit as coral. This was prevalent in Vaishnavite religious literature in Tamil Nadu and literary works in general in Kerala.
Here is th index of Swathi Thirunal songs :
PS : Of course you´d expect Kannada , Telugu , Malayalam and Tamil ( order according to my taste ) as the primary languages in Carnatic music .