tx_c_gondolier_h_hat_nm.dds needs to be renamed to
tx_c_gondolier_h_hat_n.dds, and the mesh file
a_gondolier_m_helmet.nif needs to be placed into the
meshes/a subfolder (in the rar, it's just in a
meshes folder, which is not correct). This mesh will emit an error if you run OpenMW from the console; the error is harmless (can't find the
_nm file) since OpenMW does find the actual normal map file without a problem.