I've had a proper look at this and now fully understand the SwapFirst and SwapLast variables.
The script always splits the Title field, so SwapFirst can be set to True if the values to be split are in the Artist field (as these will be swapped into the Title field before splitting).
The script assumes it is "<Artist> - <Title>", so if it is the other way round then you can set SwapLast to True to swap them round after splitting.
I am currently rewriting the script almost completely, and in the new version these variables will not exist. Might help you for now though!