in reply to Problem in Parsing XLSX
As an abstraction for reading various types of spreadsheet-type items, I can recommend Spreadsheet::Read. Install the support modules for your particular flavor of spreadsheet, and you don't need to modify your underlying code that reads spreadsheets. The resulting format is a bit low level, but that is also the type of output that many of the other format-specific modules provide.
I have not had a need to find a similar module for a writer.