I think a big part of the problem was the compressed timeline. IIRC the movie started in 1944, shortly before her death. In reality her performances had gone on for years. She started making records in 1941! I mean, just think about it. In that era nothing got done quickly, certainly not putting on grand performances in two halls, making at least one record and distributing it, hiring and rehearsing a new accompanist, etc. She died on November 26th, 1944. Even if the movie started on January 1st that's only just shy of 11 months to do all that.