What a weird connector! I can confirm that they aren't reverse gender GX16. The screw thread is the same, but the plastic housing diameter is different. I tried mating Yihua's 716C tweezer’s male plug with a GX16 8-pin female housing, but the GX16 is a wee bit too big. The pin thickness is also different. So, it looks like Yihua is moving to proprietary circular connectors for their latest stations. What's worse is the plug and strain relief assembly is molded so you can't access the solder terminals without cutting the boot open.
I've attached images of the plug. Apparently, they designed it to be modular. It's composed of two sections - A flexible boot with molded strain relief, and a hard plastic housing for the male pins. The plastic housing is a module that can be inserted into the boot. The boot is a keyed receptacle with female contacts in it that mate with male pins at the rear of the plastic housing. It took quite a bit of effort to pull the housing free of the boot, but hot air and shimming helped weaken the adhesive. I don't recommend trying it yourself though, because I'm not 100% sure the procedure was damage-free.
Even though Yihua's different station models have distinct housings (pin counts, configurations), I'm guessing they only need to produce one cord type. This modular approach prevents damage or underperformance from plugging in unsupported handles, and enables on-demand production of any handle/cord combination as needed.
As far as I can tell, the quality of these proprietary connector assemblies is pretty high. The investment in custom tooling needed to manufacture them can’t be cheap. Which is surprising considering the company’s past reputation for cost-cutting. These upgraded new stations with their proprietary connectors and higher prices make it clear that Yihua is making aggressive moves in the JBC compatible space. Let’s hope they’ll let us buy the connectors separately so we can build adapters, extensions, and mods.