A late good evening David.
I’ve just had a look. First and foremost, far be it from me to critique someone else’s spiritual ideas or comment on how something may indeed reveal itself to them. Furthermore, I think we have to ask ourselves this: do we see Woden, Gwydion, Cernunnos and so on as discrete entities, or do we see them as manifestations, or even an individual’s revelations, of the same truth? This really does depend on a person’s own spiritual world view. I think someone coming from a panentheistic angle might well take the latter route, which is fair enough.
On the other hand, and leaving aside this particular example, generally, I’d be careful with Cernunnos, we don’t know anything about Cernunnos’s story and we really only have iconography and rather short inscriptions to go off. A really “hard science” academic might even question whether the Gundestrup cauldron can be “proven” to represent Cernunnos at all since we have no engravings, i.e., names, on it. Personally, I think that would be a little too sceptical, albeit what we’d rightfully expect from an academic within an academic context. And here, perhaps, is also the doorway, or at least the keyhole, to something – Cernunnos defies our definitions and in order to find him, if it is he who we are genuinely seeking, we have to work on our own personal revelation.
You might find the information here interesting: http://www.deomercurio.be/en/cernunnos.html
Re Gwydion, well, some could possibly see a link between Cernunnos and Gilfaethwy fab Dôn in that in the Fourth Branch, Gwydion is transformed into a stag, then a sow and then a wolf respectively, while Gilfaethwy fab Dôn, his brother, becomes a doe, a boar and a she-wolf – male and female alternating each year. So, we have an animal connection, and – especially – a connection with antlered deer. Having said that, I’d also exercise caution with this interpretation owing to the fact that Cernunnos is invariably depicted as a horned god, an antlered “deer spirit”, whereas the two brothers in the Mabinogi only assume these forms because they are transformed into them as a punishment by Math fab Mathonwy.
Anyway, that’s my fourpence worth. I hope it is of some use to you.