In Big Wanda, she and Big Daddy ( Wanda's father) agreed they did not like who their children were married to, but they liked each other.
In Presto Change-O, Mama Cosma had the 9 hour flu. She was so ill that she forgot that she hates Wanda and she treated Wanda nicely and treated Cosmo badly.
It seems that since Poof was born, Mama Cosma with her daughter-in-law--while they still have some obvious issues, Wanda seems to have at least developed enough trust in her mother-in-law to look after Poof when she, Cosmo and Timmy have to leave him out of something.
She is similar to Marissa Benson from
iCarly. It was revealed in Apartnership! that she hates any woman (particularly Wanda) that marries Cosmo.
Both Mama Cosma and Big Daddy didn't go to the wedding of Cosmo and Wanda.
Cosma in Central and Eastern Europe is the genitive case of Cosmo, so Mama Cosma can be translated as Cosmo's Mother.
Mama Cosma's hairdo is most likely inspired in Marge Simpson from , which The Simpsons Butch Hartman himself is a fan of that show.
She is mentioned in Dimmsdale Tales by Carlsbad (Cosmo) in the third story of the episode. She is referred to as mother.