The following missing files are needed:
- libsndio.so.6.1
- libtiff.so.5
- libwebp.so.6
- libfluidsynth.so.1
- libFLAC.so.8 (not in AdditionalFilesForLinuxAntix.zip)
Additionally, using ldd reveals that libfluidsynth.so.1 depends on libreadline.so.7, which is also not installed. (I do have a libreadline on my system, of course, but it’s up to version 8.)
Interestingly it appears that libSDL2_mixer-2.0.so.0 links to two different versions of libFLAC: libFLAC.so.12 (which I have installed) and libFLAC.so.8 (which I don’t).