Clearly more samples would give a higher confidence that whatever paterns showed up were meaningful and not just statisticalnoise.

On the other hand, the Cernunnos map shows that most depictions are in that same hilly uplands area, as far east as the limes and then east and slightly south to the center of gaul; with some stragglers on a line towards Bordeaux on the Atlantic coast and towards the mouth of the Seine on the Channel. The south of Gaul (Roman province) and Armorica (Brittany) are noticeable gaps in the distribution.

I doubt a cult center can be identified any closer than 'east central Gaul'. But that is already a much tighter area than 'all Continental Celtic speaking areas'.