if you wrote the exact sentence "ce guitarist libanais joue aussi du piano", it is because of "guitarist" with no "E" at the end which is an english word and does not exist in french. in french it is "un guitariste" or "une guitariste".
Why is not "aussi" in the back of the sentence? "Cette guitariste libanaise joue du piano aussi."? Is it possible? In some language you can move these words depending on the context. Can you do it in French too? Thank you so much for your feedback