Could a corps artillery unit on a cliff-hexside hex still provide ground support if an enemy unit is adjacent to it, on the opposite side of the Meuse River? Also, is it assumed that a cliff-hexside does not exist in between hexes 4609/4608?
Eg: Allied corps artillery is on hex 4608; German infantry unit is on hex 4509. Would the Meuse River cliff-hexside separating these opposing adjacent units still allow the allied artillery to be able to provide ground support to any unit, whether or not the units receiving the artillery support are across a cliff-hexside? Likewise, in this same example, could the allied artillery in hex 4608 directly attack the adjacent German unit in hex 4509 as long as other allied infantry units are participating in the attack on this unit as well - so long as the allied infantry are not attacking across any cliff-hexsides?
Adjacent to Enemy.
I'd have to say adjacency (Rules 10.3) counts at all times regardless of the Meuse River. Being adjacent gives smaller weapons like mortars and machine guns a chance to shoot at the artillery unit.
The best place to ask these questions for Bitter Woods is over on consimworld.com where the designer hangs out.