There's a easy workaround.

The /usr/share/locales/install-language-pack script, used in the postinst of the language-packs packages, invokes /usr/sbin/locale-gen.

locale-gen makes some work and finally it executes localedef, that hangs up. Looking the "ps -aux" output, copying the localedef execution order, deleting the option "--no-archive" it works correcty. It's a mistery, the problem is present when the locale information is stored in locale_country.charset directory inside /usr/lib/locale/, for instance, es_ES.utf-8.

This locale-gen shell script uses the /etc/belocs/locale-gen.conf conffile of belocs-locales-bin package, which has the variable ARCHIVE with the "no" value. By changing this value to "yes", the locale information is stored in one unique file /usr/lib/locale/locale-archive. And the most important, then localedef works, does not hangs up. Now we can install, reinstall language-packs and so on.

Greetings and a lot of luck