Hi, typically short only are pretty risk since there’s no actual limit to the losses I guess. It wouldn’t be that useful, some markets have a long bias generally such as gold but why trade a market with a short bias?
The opposite entry signal is used if you have an open position it will either ignore this and maintain the original position and wait for tp/sl or close OR if its reverse then it will close the position and open the opposite position (so long if was short for example).