I did some research on the worship of Santoshi Mata and though her name does not appear in the Ved-Puranas, the worship of Santoshi Maa is of utmost relevance in the “age of the Kaliyuga’ as everything is boiling down to the satisfaction of the needs of the commoner. The various manifestations of the Mother Goddess should not be restricted to pre-Vedic and Vedic times only, and even learned scholars like the Shankaracharya Swaroopanand Saraswati, should not shut their minds to the fact that the Mother Goddess will surely manifest in the troubled time of the Kaliyuga.
Coming back to Santoshi Maa, she should not be associated with any Male Deity, not even Ganesha, who is portrayed as her father. Ganesha in this context should be seen in the Non-Dual aspect as the Ever-Existent Maha Ganpati, from which the Shakti Santoshi Mata emerged.
At the same time, I do agree with the strict rules prescribed for the worship of Santoshi Mata, including those related to fasting. However, at the same time the restrictions on the consumption of sour and pungent food items like curds, buttermilk, tamarind, lime and such other items mostly related to Milk is most relevant and forms the root of my findings that Santoshi Mata is the Goddess of the Kali Yuga.
At the same time, I do not wish to divulge the reasons and the relations between Sour Food [Milk by-products] and Santoshi Mata and why such food is to be avoided while worshiping the Goddess, especially on the days of fasting. Those engaged in the worship of Santoshi Maa, should ignore the likes of the Shankaracharya Swaroopanand Saraswati and continue their devotion towards the Goddess.
You will be hearing more on this and the Pure Form of God/Goddess, which has emerged in the Kali Yuga.