And it's pretty common for F's to misinterpret the questions.
Just as common as it is for MBTI tests to be written poorly
OP, your mom sounds ENFJ from your description. Being a feeler doesn't mean someone cannot use logic, but it's usually just not cut off from ethical values. Maybe that is what seems "inconsistent" to you.
An intuitive is likely to enjoy questioning things also. I think some NFs have copped to enjoying playing devil's advocate, myself included, although I would call it just playing with different perspectives to clarify an issue.
"Charlotte sometimes dreams a wall around herself. But it's always with love - So much love it looks like everything else. Charlotte Sometimes - So far away, glass sealed and pretty." - The Cure