I'm not sure I understand your question. Motor-wise, your child is using her left hemisphere while she is using her right hand. But yes, in other instances or while exhibiting other skills, she can be using her right hemisphere.
Your child's ability to spell may be related to how she is being taught- current practices may or may not be reaching her, if you will.
Does the teacher mode suit her learner abilities or learner preference(s)? Perhaps she needs to review phonics? There are a lot of variables in this situation.