I do have an idea of what went wrong. I just helped another fellow the other day on ATAG, he was having the same problem. He extracted the core.dll into main folder of CLOD when the correct path to place it it is:
WhateverDRIVE:\Program Files (x86)\Steam\steamapps\common\il-2 sturmovik cliffs of dover\parts\core ---->place core.dll here
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