I'm helping an English-learner to practice for an English exam that includes an oral part. At one point she used "even more" in place of something like "furthermore". It sounded odd to me so I told her that she should use something like "also" or "furthermore" instead. She told me that an English teacher that she has been using told her to use "even more" because "furthermore" is too formal (the exam actually tests if you can use casual American English speech properly so you can be understood by other Americans). I later found out that the teacher is possibly British (based on their accent in a couple youtube videos I've watched). I looked up "even more" on Google and can't find any usage of the phrase that is equivalent to "furthermore".
Here are my questions:
Is this a British English expression?
Could this phrase be understood by Americans to mean the same as furthermore?