There may an etymological problem here, the Gaelic word Carn means 1) a heap of stones 2) rocky hill top . When applied to the latter it is not because it has a 1) at the summit , most hill tops these days do , but it is due to geology . 1) became a Scots/English term applied to prehistoric up to contemporary structures made from boulders . Therefore the hill name does not suggest a monument .
There seem little doubt that the Welsh sites were genuine B.A cists with covering cairn and there are plenty of relatively high Irish passage graves but there has been no similar scottish finds at that height I can think of . Of course that may be due to lack of excavation .