The task of automatically formatting documents is always a PITA. Using LaTeX, as already suggested, is probably the cleanest way.

The only real problem in LaTeX approach is that the document templates are to be written in TeX, and it's a skill not so easy to find, particularly when you expect to have several dozens of templates to be done. Cheap. Fast. Hopefully aesthetically valid.

We are working on another approach that I hope to became, eventually, a CPAN module: a Perl object which takes an ODT file (OpenOffice document) containing a template for the document with markers to be replaced/expanded with data passed to the object in a structure (HoAoH...).

At present I have implemented conditional blocks, iterative blocks, some aggregate functions on input data, and formatted data substitution. It apparently works rather well but it is really ugly code and certainly not extensively tested.

If you are interested I can pass it to you, or make it a CUFP node but I'm really ashamed of the code as is now...