It looks like there is a lot of boilerplate code in tax.xml. For example, for the Swiss tax codes 400 and 405, discussed in this other thread, the code is almost identical for each tax code.
For all countries in the EU customs union, there are almost identical patterns for intra-community VAT and similar concepts.
Has anybody looked at strategies for generating the tax.xml records like this using XSL transforms? This would make the files easier to create, easier to read and easier to troubleshoot.
XSL transforms could also help to swap strings in different languages.