There would be no sestinas - as least as a function of language rather than sound or shape - without language, so is the sestina form mind independent only if language is?
What about forms in painting? The shape someone has painted their muse exists independent of anyone seeing it (at least if paint is real), but perhaps it is not a "cubist" form independent of minds, in a similar way to if beauty is mind independent.
What about musical forms? Is this a rondo independent of anyone ever hearing etc. it?
What artistic forms are mind independent and in what way?