Where does “ソワカ” come from?

ソワカ (Japanese) comes from Sanskrit स्वाहा — well-said.

ソワカ (Japanese): 娑婆訶, 莎訶, 蘇婆訶, 薩婆訶 svāhā

Definitions

Step	Language	Word	Meaning
1	Sanskrit	स्वाहा	well-said

ソワカ — Etymology, Origin & Word History | Etymology Explorer