Following this: http://translatewiki.net/wiki/Thread:Support/Problem_with_RevisionDelete_messages
It seems that, no matter the language you use on your preferences, parts of the log message are shown on wiki's local language. See http://test.wikipedia.org/w/index.php?title=Special%3ALog&type=suppress for reference (set your preferences in a language different than English to reproduce).
As you can see on that thread at translatewiki, those messages are internationalizated. If possible, please fix this.
Best regards.
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Severity: normal