Somethings not adding up to me here, though I must admit I'm not an expert on charging EV batteries. Why was there sustained 18A charging session previously when you haven't seen these figures since you replaced the plug/socket? Having had a quick read about EV battery charging characteristics there was nothing there that indicated charging rates would vary upwards at higher battery levels.
2 amps above the rated 16 amp limit isn't likely to be your problem, providing the plug and socket is in good condition. I'm highly suspicious of the numbers you are seeing.
The entire EVSE was replaced, the old one was reporting up to 18.6~A, the new one isn't reporting above 15.2A. I didn't re-test the old one after the socket was repaired because I didn't want to put the effed up EVSE's plug anywhere near it.
The 'higher amps at higher %' is still a hypothesis tbh (posited by sparky). It consistently drew 18+A when plugged in after I got home from commute at 20-30% SOC. Whenever it did draw only 14A, I recall the car had a much higher SOC. I didn't do any testing because of aforementioned bung plug.
I don't know why it was drawing that much but it's been sent back and hopefully the manufacturer can tell us when they inspect it.
In the meantime I'm going to keep a close eye on the amps and keep my ears out for buzzing.