Columns follow the order of the measures. A predictor a measure does not
cover is NA in that measure's column: some backends report only the
predictors used in a split. A measure named variable or fold, or one
repeating an earlier column, is labeled "<name> (measure)", since those
column names carry the table's structure.
The table holds the values only. What each measure quantifies, the cases it
was computed on, and how it ranks predictors are on the measure itself:
get_varimp(model)@measures[["<name>"]].