In the two you've listed as not working, you have a minor typo where you're missing a colon between Calc and Today. It should be: Date::Calc::Today.

In the other one, you haven't shown your output which leaves me having to guess what the problem is:

• The format you seem to want doesn't match the pattern you're using for sprintf.
• The documentation for Date::Calc shows:

  ($year,$month,$day) = Today([$gmt]);
  [download]

  so, clearly, that's not going to provide you with hours, minutes or seconds.