Question on vehicle frames

Been messing about with replacing broken frames on a vehicle. When you add a new frame piece you can select between various shapes but there is only two L shaped corner types so the frame piece for an upper-left corner or bottom-right is not available but they do exist on vehicles you find. Is there a way to flip corner pieces? Does this even matter and are the frame shape types purely an aesthetic choice? It looks like I can add a ‘wrong’ corner frame and the vehicle appears to run fine so maybe the only problem is that it looks funny.

It’s there.

Ah! It is there. It was the font I was using that messed it up. Terminus shows it fine. Thanks.