hello schmecks,
When you run retroarch command standalone, remember firt to set up LD_LIBRARY_PATH environment variable for the shell you are using (that means to set it up any time you login back).
(I forgot to mention it before, sorry)
Something like:
export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/storage/retroarch/lib
Now run the command:
ldd /storage/retroarch/retroarch | grep "not found"
After copy first batch, you could see extra dependencies needed by the libraries you just copied.
I would recommend you to only copy what is not already present on LibreElec, I would prefer native OS libraries.
Another thing you could try, is to specify Lakka image "/usr/lib", in your case I think it is: "/media/root/usr/lib", so it will be something likes:
export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/media/root/usr/lib
And then try running ldd like:
ldd /storage/retroarch/retroarch | grep "/media"
And whatever cames from the image is what you need to copy.