Hi,
I don't find any clear rules on when to add/update translatable strings (from the developer point of view). I have a suggestions :
master (dev) : - freely add and change translatable strings
when preparing a future stable (4.0-alpha/rc) - no new translatable strings - no updates that changes the content/meaning of a translatable string (but exceptions allowed after discussion on mailing list) - updates fixing typos and grammar are allowed
current stable (QA_3_5) - no new translatable strings - no updates that changes the content/meaning of a translatable string - updates fixing typos and grammar are allowed
old releases - no maintance on translatable strings (no new strings, no fixes on existing strings)
What do you think? BTW : the reason I mentioned allowing grammar/typo fixes in current stable, is because it has almost no influence on the translating process. A string with an fixed typo does not have to be retranslated.