Agreed.Â
Moving into difficult terrain reduces the MA to 2UD, which exceeds the distance moved at that point - so the group may move up to the edge of the terrain (possibly more than 2UD), and then ...
After initially thinking you should be able to charge at this angle, I now think probably not.
A charge by the whole group is not valid. The paths of X and Y are aimed at C and B, but go ...