C3PX said:

From what I read while trying to look into this, Kenner was in charge of naming many of the background characters that got figures, so if that is the case, and the names came from them and not anywhere else, then I concede that the original names they gave them were initially correct and the change may have been made retroactively.

That would change everything! If the script and novelization call the humanoid "Tuckuss" and the toys call him "4-LOM" and the droid "Zuckuss" and Kenner came up with the name "Zuckuss" than TUCKUSS is the canon name and Kenner messed it up by calling him "4-LOM"!

So many layers! I just go with my gut, and my gut says Kenner got a picture of the line up that said "here are the guys" and they either made up names for those that had none, or the names were given backwards, or somewhere down the line from toy design to packaging someone got the names crossed. They would look very similar if the toy wasn't painted.

To me, 4-LOM is the droid and Zuckuss is the humanoid. It just makes sense.