Sometimes it may be useful to put the The or an A that many movie names begin with (e.g. The Avengers) at the end of the name (i.e. Avengers, The) to improve lexical sort order. You can do that in your custom format, either via the String.sortName() helper method or some custom regex replace.
Note that most software expects the file name and the database entry to match exactly. If you mess up the file name like this, then FileBot and any other 3rd party software may have trouble making sense of the file name in the future.
If you use TheMovieDB then the series name {n} will never include the series year and thus { n.sortName('$2, $1') } will always work as expected.
If you use TheTVDB then the series name {n}may include the series year as part of the series name. In this case we can use replaceTrailingBrackets() to remove the (1956) from the series name: