acordeonista (both genders)
accordionist
an "accordionist"
Mark Twain called the accordion "the stomach Steinway."
The best thing to do is to call the person by his or her name.
A "harmonicanist" is what a person who plays the harmonica is called.
Chilean
Canadiense
A person who plays Scrabble is called a Scrabbler. (unofficially)
A female person from Spain is called "española" in Spanish.
A drummer or percussionist plays the drums.
harpist
a baritonist