I found the problem, our ImageMagick libraries have different names than those spected by spumux. This happened to me with another program and the fix for that program worked also for devede, that is why I didnt note it, sorry. I installed devede in a VM and I got the same error as you, I opened /usr/bin/devede and noted that they check for spumux using the output of spumux --help. That was very clever because the output of spumux --help was not indeed the one you would expect.
Anyway, the fix:
ln -s /usr/lib/libMagick++.so /usr/lib/libMagick.so.10
ln -s /usr/lib/libMagickWand.so /usr/lib/libWand.so.10