Re: odd template problem with hash of arrays

>    [% sites.$edate.site = [] UNLESS sites.$edate.date.exists %]
>    [% sites.$edate.site = [] UNLESS sites.$edate.date.exists %]

I think this is probably your problem, but beware, I am only
guessing! I haven't really looked thoroughly at your example
but those lines above caught my eye. You probably want
explicit SET directives:

  [% SET sites.$edate.site = [] UNLESS sites.$edate.date.exists %]
  [% SET sites.$edate.site = [] UNLESS sites.$edate.date.exists %]

An explanation can be found here:
http://www.template-toolkit.org/docs/plain/Manual/Syntax.html#Capturing_Block_Output

HTH, Hans