Maxxing out the trader track in Stone Age: Style is the Goal
There is actually a difference between the wording of the English and German rules, that I think is significant.  The English rules say:


  (Each time the player moves his marker forward  on the trader track,
  regardless of how far, he takes 2 decorations.)


In the German, by contrast:


  (Jedes Mal, wenn der Spieler auf der Händlerleiste vorrückt, unabhängig
  ob 1 oder 2 Felder, erhält er 2 Schmuck.)


To roughly translate that, and highlight the difference: "Each time that the player on the trader track advances, regardless of whether it is 1 or 2 spaces, he takes 2 decorations."

I think it's a lot clearer from that wording that getting the decorations is specifically linked to advancing along the track, and that "advancing 0 spaces" was not meant to count as advancing.  As such, I'd come to the opposite conclusion to user1873's answer, and assume that the designer only meant you to be able to get decorations while making real progress along the trader track, and not to be able to milk it for more decorations after having maxed it out.