Even FactoryTalk View doesn't have a native clock update feature, so you probably won't find one in Wonderware.
The usual roll-your-own method is to use scripting or a macro function in the HMI to write the values of the year, month, day, hour, minute, and second into a set of registers in the controller, then trigger a Set System Variable (SSV) instruction to the WallClockTime object.
The SSV works exactly like the GSV you are already using, but in reverse.