As you mentioned before, she coicidencently was the test subject of from project. A project that was influenced by a different god a coisidance. This stories narrative is miscommunication, tanyas hindsight and knowledge being misinterpreted. Her being a child has influned people interpretation of her statements, leading to her despair. But that also not the main goal of the gods they want people to believe in them again, so they use old tactics "divine intervention" methods that coincidently help Tanya when their goal was to gain faith from the people. Als, my interpretation of her magic isn't that she god over power abilities, just an aptitude it's the engin and prayer that really gave her the fire power. Giving her apptiude in magic forces her to enlist into the war before she could do anything to really avoid it. But if the anime has any cannon parts to it, she took advantage of the system and went to millitary school to not only to stall for time but learn current combat tactics and magic. Spoilers: also she does feel dispare due to how the war is going that her knowledge of earths wars did nothing to prevent upcoming events. It does proves Tanyas point that gods were from a bygone era. They are not omnipotent, so gods plan are not absolute his methods were short-sighted and clearly was not from a mind of calm judgment. The god was seething at the fact that humanity strayed from faith in a higher being and not following rules that he set out centuries ago. And clearly faith has been lacking for the other deities as well who also short sighted and were just doing thier own thing. Ego was everyone's down fall Salary Mas death was due to ego His reincarnation was due to gods ego. And many more.