Very nice playing! Excellent! It‘s a pity such great composers like Liszt didn‘t write anymore solo pieces for trombone. The trombone is underrepresented in the classical and romantic repertoire. Luckily, nowadays the solo literature has been largely expanded by modern composers and the impact of trombone heros like Christian Lindberg.
I bought a copy on a German sheet music site three years ago but I just found it on IMSLP. It takes a little digging but it is very much there. I've never seen anyone post links in comments but contact me directly and I can send you the file. It is definitely public domain.