Not all questions have been answered to clarify the situation, so next question ...
5. The string ', The' is a constant literal, how could it be sorted?
6. Do you want to filter the column entries to detect only entries, which contain this string?
A shoot in the dark ...
You can try to sort the column ComposerSort, which displays the content of the tag-field COMPOSERSORT, by the content of the corresponding tag-field COMPOSER.
Doing so, all the COMPOSERSORT entries like 'Artist, The' will be sorted in the same order as the corresponding COMPOSER entries like 'The Artist'.
Could this be the solution for what you have in mind?