why is (Noen ganger er hun her) considered best translation instead of (Noen ganger hun er her)
because when an adverb is at the start of a sentence the verb has to be second. They call it the "V-2" rule here. https://www.duolingo.com/skill/nb/Adverbs
Would, "Hun er noen ganger her," work as well? If so, is there a difference in the emphasis?