I think both are real because phenomena at least can exist for more than one person, it's more real than solipsism and it includes the experience of the senses and not just the experience of our own internal thoughts or imagination.
So I'd say there's a sense the imagination is real - we have an imagination - but there's a sense it isn't.... the latter sense being often when we ask "Is it real?" we are asking "Is it unimaginary?"
So I'd say there's a sense the imagination is real - we have an imagination - but there's a sense it isn't.... the latter sense being often when we ask "Is it real?" we are asking "Is it unimaginary?"