You can set a value by linking it to another value with action parts, but if you were going to do that, then you might as well just manually do it anyway as it's the same amount of action parts, no?
Anyway, in the set value action part there's 2 value parameters. the first one is the value you want to change. if you specify a second value then it will set the value the same as the linked value, but like I said, it's kind of pointless because you would still need to do 2 set value action parts to change both values.
The script I wrote/shared is an event listener that listens out for when the set value action part is executed, then does whatever you have told it to do, which in this case would be changing the value of value B to value A if set value action part was used on value A.
The editor doesn't contain any functions like that as it's purely for visually creating your games - maybe it would be possible with the visual scripting section? I haven't looked into that side of the editor yet.