Enable mass rename of columns during the transform data process

Multiple data tables are often joined using the "Add as columns to" option. Often, the data sets being appended have the same value column names (ex. $, $ YA, Units, Units YA) which results in the subsequent data value columns having ([%C (n)]) or ($ (2), $ YA (2), Units (2), Units YA (2)) using the specific example where n is the data set number appended into the data table. Usually, the data columns being appended have meaningful column names that can be derived by appending a prefix or suffix to the original column names. Using the example measures above ($, $ YA, Units, Units YA), an example solution using the "Concatenate" option in the "Change column names" transformation could be "concatenate(Category," ", [%C])" that will yield the column names Category $, Category $ YA, Category Units, Category Units YA. It seems part of the solution is already in place as the "Concatenate([%C])" expression works but falls apart when modified to include any other character to be concatenated.