How to electron count bridging ligands?
In the covalent (L) method, $\mu$-hydrides should be treated as a normal hydride (1-electron ligand) for one metal. The $\ce{M-H}$ bond itself should be treated as a 2-electron ligand for the other method. This explains the two entries for hydride in the link you provided:



Cyano-ligands are isoelectronic to carbonyl ligands, so I'll leave that to you as an exercise to figure out.