Forum OpenACS Q&A: I18n

A possible workaround could be that you create an own locale for each subsite and each locale:
So for subsite S1, S2 and supported locales en, de you create the following new locales:
en_S1, en_S2, de_S1, de_S2.
Then you copy the existing message keys of the "master locales" en and de to their appropriate children and edit them individually.
In the subsite you can now set the supported locale manually.

I don't know if this is the best solution or what problem you can run into but it can be done very quickly. Perhaps somebody can post a better way.

because of the fact that Localization is a singleton package and can therefore just have only one instance you have to create an own locale for each subsite.

In /acs-lang/admin you have the link "Create New Locale" at the bottom of the page.

I've never tried that out so I cannot guarantee that it works perfectly but it would be the methodology I would try at first (if somebody does not come up with a better idea..)