When people translate, it is often not clear what the messages is there for. Individual messages may be part of a bigger message and, this can impact grammar. Messages may have multiple parameters and what they are is not necessarily clear from the message itself.
Betawiki became a superior environment for its localisers when it started to provide context for the messages. These messages are available as "qqq" messages. The person best placed to provide this help is the developer of the software. Second best are the people who have learned where a message appears.
Given that Betawiki supports 298 languages. The pay back for this investment in time is obvious.