Kobos don't use the filename template for their bookshelf (the index you see) , so that is just a file name
OTOH your template looks like my series index part
5.2 is because I use fractional series and proper ASCII sort compatibility
Code:
{series_index:0>5.2f|| - }{title}
01.03 - Crimson Worlds Collection
The Kobo driver can create Series info in the bookshelf, So I let the bookshelf (collections) do the heavy lifting