Well, while that is true, you can convert the feel of a character and get his important skills, feats and abilities.
So, when I'm converting my Paladin I sure as sh1t can translate Moonbeam and Misty step more or less word for word if I want to. Obviously some things work less well in Hero especially the wards, and bonuses to saving throws and other abilities which affect the D&D system mechanics. Not that they can't be built, they can, but I don't know how important all that is compared to the feel of the character. I would just use the D&D character as a base for my Hero write up.
I would just say "Your characters are now in hero rules. You were 10th level so you have 250 points to spend