You want to get the label from the scale anchor list that was chosen for a specific row of the semantic diff, correct? You can do this using the ListLabel function:
[% ListLabel(AnchorList, SemanticDiffQ_1) %]
"AnchorList" must be replaced with the name of the anchor list used in the semantic diff. "SemanticDiffQ_1" must be updated with the name of the semantic diff question and which row is to be selected.