A recording of the Symphony no. 2:III Adagio 'Pro defunctis' is available at archive.org with a hand-written note that someone contacted the conductor, Barbara Schubert, and that only this movement was performed at that concert:
https://archive.org/details/cd_francaix-korn-bresgen-weigl-compositions_jean-francaix-peter-jona-korn-cesar-bresge
More of Weigl is available at that site:
https://archive.org/search.php?query=creator%3A%22Karl+Weigl%22
https://archive.org/details/cd_francaix-korn-bresgen-weigl-compositions_jean-francaix-peter-jona-korn-cesar-bresge
More of Weigl is available at that site:
https://archive.org/search.php?query=creator%3A%22Karl+Weigl%22