Real Vewlix will have Taito tags at the very least. One on the back, upper right side and another under the control panel right side with the serial number.
Real F and C models have silver metal where the adjustable legs are and the legs do not stick out from the top. They also have lowered areas on the control panel where the ashtray goes. Later legit models do not have this difference and are a little harder to tell apart.
If it's wired for jamma and has a Pandora box it's very likely a chewlix.