In the version I’ve accessed via Hetascanlations, the Vatican is mentioned, but the character near the line of dialogue isn’t tagged as such.

Unless that was a mistake, I don’t think it was intended to be him.
There’s also the fact that in the context of the strip, we see an unknown American stand in as a spokesperson for his people’s attitude towards Christmas.

It would follow, then, that the character above acts more as a mouthpiece for residents of Vatican City, which would make sense given that there’s another clergy member placed right above him (below here
↓
).

Usually when characters are first introduced in canon, they’ll have an official title underneath them. Like this…

I also double-checked on Bamboo Thicket before I made that post to see if there were any illustrations made of the Vatican. I didn’t find any in the tags.
Unless the Japanese print version of World Stars is slightly different regarding illustrations (I wouldn’t know, but I know that strips are often redrawn), the online English version merely translates the chapters that Hima’s posted.
In that case, if you could provide a sourced image that would be helpful.