Since you're a native speaker, I was wondering if this name could be shortened or changed somehow to fit a technique name like Amaterasu or Tsukuyomi, possibly Kotoamatsukami: 天之御中主神, Amenominakanushikami "Heavenly Ancestral God of the Originating Heart of the Universe".
You'll probably recognize it as the name of the supreme shinto god. I know the "kami" can be dropped, but I kinda like the literal meaning of all the kanji. If it's possible to shorten it or something similar, I'd be very grateful if you could let me know!
I apologize for the very late reply. To answer your question, yes, 隠された戦争 translates to "Hidden War". However, note that as in every language, there are many ways of expressing oneself in Japanese. So while Kakusareta Sensou is correct, there are many terms which have similar meanings.