The only place I've seen filenames with (epub) in them is pirate sites. Not to mention that in your template, you are not splitting the series name from the series index.
As @theducks mentioned, the calibre library should be treated as a black box. The filenames & directory structure are not modifiable. You can play with the Send to device or Send to disk templates for exports.
If you are trying to set metadata from the file name, you can check such message threads as
Adding metadata via filename for some help.
If you are still wanting the filenames in the calibre library, see this message:
Want to change folder structure or file names in the Calibre library? from 2011. Nothing has changed.