Schubert Grazer Fantasy (D 605a)

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This is my third favorite piano piece I have ever heard and is remarkably underrated. However, I have a question about copyright, since I want to learn it. It was published in 1969, meaning not public domain under US copyright law. However, on the IMSLP copies, it says it is public domain but questions the validity of this status. I'm not trying to include it in any media or anything, just learn it and maybe re-engrave it for insight. Do you think it would be fine to learn from the 1988 Barenreiter edition here? https://imslp.org/wiki/Fantasy_in_C_major,_D.605a_(Schubert,_Franz)