You're forgetting that copyright terms extend to the end of the calendar year. Hindemith's copyright term in Canada extends to 11:59 PM on 12/31/13 so he will not be free in Canada until 1/1/2014. We would not allow any uploads of his work until after that date. There are a few items on the USA server (which regular users cannot upload to) which were published before 1923 and are thus free in the USA. BTW, Worldcat is no place to determine the USA renewal status of a work published in 1945. This information is found only in the Catalog of Copyright Entries
. You would need to carefully check the renewal volumes for 1972, 1973 and 1974 to determine of the 1945 score was renewed or not. (It almost certainly was). Even if by some miracle it wasn't renewed, the work would be eligible for GATT/TRIPS 'restoration' as it was very much under copyright in its country of origin as of 1/1/1996.