A translator really wouldn't be able to translate her emotion, but at least if she was speaking primarily in Spanish people could see her body language and hear her inflection when she is speaking without an extra level of processing, and then later hear from the translator what exactly was said. I guess really what is unfortunate is just that there's any language barrier between the family and some officials and some members of the public in the first place. There's not much that could be done to truly fix it. A very experienced translator would be able to choose their words carefully to better convey the nuances of what was said in the original language, though.
As for the fact that she was born and went to school in the U.S., that's definitely true and that's why her English is as good as it is. However, it's pretty apparent she likely spoke Spanish most often at home, probably learned Spanish before English, and considering the large Hispanic population of Bridgeton, she likely often also spoke Spanish with her peers even in school as well. All just MOO