Why not include the "[]" in the Song Title Version and then just use [NAME] [SONGTITLEVERSION] as your calculated field?
Or if you want to have Song Title Version without the "[]" and then the calculated field have the "[]" then create 3 fields.
SongTitleVersion
SongTitleVersionCalc
Temp
Make Temp a calculated field of "[SongTitleVersion]". This should automatically fill Temp with the values of SongTitleVersion with [] around it.
Use the Copy Fields tool to copy the value of Temp into SongTitleVersionCalc for only those files that have a SongTitleVersion. You can easily use the sort function to filter out the ones that don't really have anything. Now you should have 2 fields. One with just the Song Title Version without [] to display as a column, and one with the [] to be used in your calculated field along with the Title. Temp was only used because it was easy to create the [Song Title Version] format you're after, without being left with a bunch of files with [] listed in them. You can delete the Temp field now.
Then make your calculated field so that it's "[NAME] [SONGTITLEVERSIONCALC]".
This should give you what you want... if I'm following my own logic right. It's hardly an automated thing, but it should at least get you caught up, and then you can just keep things up to date the way you want as you add new files.