Yes,
I was using the TH10 to control a water heater and it did melt, mainly in the area around the fuse. Itead replaced it with what they claim was an updated product and I think they claim that the solder in the tracks was incorrectly specified. The current was only 8amp max!
IMHO I would not want to put high current through solder tracks and in the past I have had a fire as a result of a smouldering PCB in a non-fireproof box. The devices are great but perhaps Wifi is not, especially when enclosed in a box with other stuff. If you want high current, then drive a relay with Sonoff.