I never came across Omni benevolent while reading dozens of Spiritual Books during my 10 years stay in India
Omni Benevolent seems a Christian, Atheist or Abrahamics thingy
It's a Christian thing. Atheists don't believe in a God, omnibenevolent or otherwise.
I can imagine, as it is easy, that a "smart" Atheist debater invents "Omni Benevolent" to disprove God or something like that, but as this description makes no sense to attribute to God, it is useless, but fun maybe for debate sake.
Imagine whatever you like. And feel free to suggest that atheist arguments against religion focus heavily on Abrahamaic faith. It's true, imho. But this isn't an atheist invention or strawman, and I'm somewhat bemused why you'd assume that.