Comment 18 for bug 36145

The rename from 00tetex.cnf to 10tetex.cnf seems intentional:

tetex-base (3.0-15) unstable; urgency=high

[...]
  * Rename language.de/00tetex.cnf to 10tetex.cnf, so that it really sorts
    after 00tex.cnf. Transitional code missing. [frank]

 -- Frank Küster <email address hidden> Thu, 2 Mar 2006 15:40:17 +0100

The problem is that /var/lib/tex-common/language-cnf/tetex-base.list still has "00tetex" instead of "10tetex".

But, for some reason, even though my language.dat now includes 10tetex.cnf (and I've run those two commands), I still don't get any hyphenation.