If you really want it, though, I've included a version here which duplicates what SourceMod does with ShowActivity.
While I was at it, I fixed a bug in ReplyToCommand not setting the translation target correctly and also added ReplyToCommandEx.
None of these has actually been tested, though.
colors-tester.smx is a quick plugin to test the CShowActivity, CShowActivityEx, and CShowActivity2 responses. Note that {teamcolor} is set to the client argument's color since it's logging what they are doing.
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Not currently working on SourceMod plugin development.