French term (edited): couché moderne satiné de 300 grammes

I think that's along the right lines, though I mustn't claim excessive confidence, this is extrapolating a bit outside my personal knowledge.

not at all sure about that 'moderne' though — I wonder if in fact that implies that it isn't actually truly 'coated' stock at all, but what we refer to as 'super-calendered', which is the cheaper variety that came along to replace 'proper' coated stock — that theory would certainly be consistent with the fact that it is only 'satin' finish, and not high-gloss (hence the addition of spot varnish to give selected parts a glossy finish)