A person's backside includes the buttocks but that's not what you said in your original remark. Several versions I consulted did not translate the word as buttocks. If someone says "Don't turn your back on me," normally that doesn't mean "Don't show me your buttocks." The word numbered 0268 that you say means "buttocks" is not translated as buttocks in the versions I have i.e. ESV, NRSV, ASV, ERV, KJV, LXX, WEB. Douay and others. The LXX doesn't translate it as buttocks, either.
I find the idea that God having a buttocks was a fundamental truth of SDA that should be shared with the world, according to the general conference, hard to believe.