Tolong Siki was developed rather recently for the Kurukh spoken language. Previously, Devanagari was used (and is still used in large part a decade later).
Tolong Siki is one of the few languages that was created from scratch collaboratively that we know of. For most writing systems, their origins are lost in antiquity. Many clearly evolved rather than “were created”. For recently-created writing systems, when we know who the creator was, there was almost always single creator. Tolong Siki is an exception: while Narayan Oraon (a medical doctor) gets most of the credit, he collaborated with Francis Ekka (the former director of the Central Institute of Indian Languages), Ramdayal Munda (former Vice Chancellor of Ranchi University), and Nirmal Minz.