The copper (or brass) screw touching the terminal looks good electrically and thermally.
To understand what I'm describing you must make a mechanical drawing showing the entire screw end to end. Show the sandwich including the screw head, the terminal, some washers, the plastic, and any other hardware.
All of these items must never cold-flow under the constant pressure of the connection. They must have a thermal coefficient equal to that of the screw. Copper (or brass) hardware meets the requirement.
If your plastic enclosure is part of this sandwich and is under compression, it must also meet this requirement.
[edit] The diagram I added hopefully shows the consequences of using a plastic which cold-flows over time. [/edit]