I don't know of anyone else with quite this interpretation of the Zornhau-Ort from both Goliath & Paulus Kal, so, yeah, it wouldn't surprise me if I'm wrong. I believe that the zornhau portion of the zornhau-ort is done with a backwards passing step. Here is my argument to make the case:
First, let's look at the Paulus Kal Zornhau-ort.

Here are my assumptions about the combatants *before* the actions shown in the plate:
-Right starts from a standard vom-tag position, with left foot forward. He has cut an oberhau to Left's left opening, passing forward with his right leg.
-Right is aiming, distance-wise, to cut Left with the COP [center of percussion] of his sword.
-Left starts from a standard vom-tag position, with left foot forward.
These starting positions are pretty orthodox, and supported by the texts, per the standard advice on how to stand and how to perform cuts [with stepping, matching the leg with the side that the strike is thrown from, etc...pretty standard]. I can quote the relevant text if necessary, but I think we are all pretty much on the same page here?
Here are my interpretations of what is shown in the plate:
-Left has, in the Nach,
passed back with his left leg while simultaneously cutting a zornhau to the centerline.
--He strikes Right's blade powerfully out of the centerline, ending with his point threatening the opponent, and his elbows half-bent, in a biomechanically stable position, poised to act.
-As soon as Right's blade is struck, Right withdraws his blade back to a more defensive posture.
My reasoning for the bolded part above:
-Left's body position appears to be in a "withdrawing" mode. This is obviously up to interpretation, but to me it looks as though he has just stepped back, into a back-weighted stance.
-The distance of the combatants.
--If Left had stepped forward [another explanation for why his right leg is in front], the distance would be much closer than what is shown, since Right was already collapsing the distance to be able to hit Left's opening with his COP.
Now let's look at the Goliath zornhau-ort plate:

My assumptions for the starting postures are the same as above, for the same reasons.
Here are my interpretations of what is shown in the plate:
-IMMEDIATELY following what is shown in Paulus kal:
-Left has now thrust his hands forward, up, and slightly to the left, while simultaneously shifting forward from the back-weighted stance shown in Kal. Notice the slightly forward leaning torso, and the raised back-heel.
-Right is leaning his torso back, away from the thrust.
Left is now biomechanically able to easily/effectively choose to make a short, very fast lunge with the right foot, or close the distance further by passing through with the left foot.
Based on the assumptions I listed above,the only way for Left's right leg to end up in front is either:
-A pass forward.
-A pass backwards.
-Stay still during the zornhau portion, then pass forward with the right leg during the ort portion.
Now, look at the distance. If Right was cutting at Left and was planning to close distance enough to hit Left with his COP, and Left passed forward with his right leg the combatants would be much much closer. Even if Left started with his left leg forward and stood still for the zornhau, then stepped in with a pass of the right leg for the ort [per Jesse's interpretation], the combatants would be much closer. At least close enough for Right to be able to hit Left on his upper opening with Right's COP. In my opinion, we don't see this distance. We a distance where Right has tried to close with a cut, but Left has stepped just barely out [or still very slightly within] Right's cutting distance.
If you do this with a partner, try each option and take a picture. Be sure that Right is actually trying to land a cut on Left's head/neck/shoulders.
-Pass backwards with the left leg while doing the zornhau portion, then stay still for the ort.
-Pass forwards with the left leg while doing the zornhau portion, then stay still for the ort.
-Stay still for the zonrhau portion, pass with the right leg for the ort.
In my opinion/experience, the first option ends up looking the closest [both distance and posture-wise] to what is shown in the plates above.
I believe the zornhau-ort is a concept/principle, not a absolute technique, so I think what you are doing is definitely a Zornhau. I just don't think it's exactly what is shown in the Goliath plates you initially linked...the Zornhau-ort and zornhau-winden plates.