I know I said the ones that just return Vote Failed may be for VoteFail usermessage instead, but there are some CallVoteFailed types that don't work. For example, TF2 reason 11 / CSGO reason 16 is supposed to be "Player not found", but it never has appeared to work correctly.
Who knows, maybe it does if you pass a userid for the second argument.
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Not currently working on SourceMod plugin development.