Should accept "mouth organ", I think.
Has been added.
Another popular name for "harmonica" is "harp" (especially in blues).
'accordion' is also correct.
I'm afraid an "accordion" is not correct that is "ακορντεόν" in Greek. An "ακορντεόν" and a "φυσαρμόνικα" are very different. Try googling them and checking the images.
Pretty strange, but interesting: "fisarmonica" means exactly "accordion" in Italian.
somebody overruled you. they're now accepting "concertina".
Yes, it was decided that we should add "concertina" it's not a matter of overruling we work as a team.