Centralising the functions must be a long term objective of the EASA, with the net- working as an interim step to consolidating the various working functions. Getting it to work will be a long shot.
Regarding the liability issues read the ICAO annex (13), as it specifically states the following:
Annex 13 To the Convention on International Civil Aviation - Aircraft Accident and Incident Investigation
OBJECTIVE OF THE INVESTIGATION
3.1 The sole objective of the investigation of an accident or incident shall be the prevention of accidents and incidents.
It is not the purpose of this activity to apportion blame or liability.
Litigation, insurance payouts, liability ect will have nothing to do with the accredited investigating authority. The courts will always decide the compensation, as it has nothing to do with factual reporting and final report submitted by an accident investigation authority - it's completely unrelated
Back to the point though, a centralised function has some benefits, so not to be dismissed out of hand