Mouse cursor
When copy/pasting a transformer, it can go quite far from mouse cursor. Usually next thing is to drag the transformer and link it to another transformer or a feature type. Could the pasted transformer be located just where mouse cursor is?
Linking
Now when a port is selected, a new added transformer is linked to the port. This could work similarly for copy/pasting a transformer. If a port is selected, and you copy/paste a transformer, it will be linked to the port.
Of course all this works for feature types too.