8.4. Best current practice concerning l10n
As a maintainer, never edit the translations in any way (even to reformat the layout) without asking on the corresponding l10n mailing list. You risk for example breaking the encoding of the file by doing so. Moreover, what you consider an error can be right (or even needed) in the given language.
As a translator, if you find an error in the original text, make sure to report it. Translators are often the most attentive readers of a given text, and if they don’t report the errors they find, nobody will.
In any case, remember that the major issue with l10n is that it requires several people to cooperate, and that it is very easy to start a flamewar about small problems because of misunderstandings. So if you have problems with your interlocutor, ask for help on the corresponding l10n mailing list, on debian-i18n, or even on debian-devel (but beware, l10n discussions very often become flamewars on that list :)
In any case, cooperation can only be achieved with mutual respect.