That is indeed the case.
Syntax:
bool triggerClientEvent ( [ table/element sendTo = getRootElement(), ] string name, element sourceElement [, arguments... ] )
Optional argument sendTo is not filled in, therefore it will send to all.
To fix that:
triggerClientEvent(source, "Emoji5:activarEfecto", root, source )
triggerClientEvent(source, "Emoji5:activarEfecto", root )
triggerClientEvent(source, "Emoji5:activarEfecto", source ) -- or for better performance