Seems like the chatter section should have a little more flexibility...

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>"Answer a message in the same language
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>Do not answer a message in a different language than the one the message was posted. If the message was posted in English, then English should be used for the entire thread. As for the most used language in the Universal Thread, English will be accepted at any time."
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>Taken from the "Replying to a message" section.
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>Thanks