AFAIK, it has always been the case that a flight that is not operated by a Skyteam airline is not to be regarded as a Skyteam flight and, therefore, does not give rise to SKyteam benefits. The
Skyteam website states:
Complimentary access to member airline lounges when you are departing on a same day international flight or connecting to/from an international flight operated by a SkyTeam member. This benefit is available to International First / Business class customers or SkyTeam Elite Plus frequent flyers
and the KL/FB site also states, with regard to Alitalia:
Lounge access applicable when holding a same day SkyTeam-operated flight ticket