Last January, the preliminary study on the criteria for independence of regulators in the AVMS directive has been published. Although, this relates to media and not purely telecoms, the criteria could arguably also be applicable for telecoms regulators. The final study is expected for later this year.
In this regards, I believe that some works could be done to harmonize the wording applicable to the notion of independence of regulators across the various regulated sectors (the legal provisions differ not only in the AVMS directive and the Framework directive but also in the directives applicable to the energy sector or to data protection). Some guidelines for such exercise could be found in Case C-518/07, Commission and EDPS v. Germany (re. data protection).