You are most correct that only Southerners have had the good sense to create a 2nd person plural where none existed in the English language. I am a bit of a Southern-o-phile, even though I was born and raised in the intermountain west. I even had the good sense to marry a southern girl (and she had the good sense to move out to the mountains with me.)
But I think there are just too few people who would be willing to use "y'all" in the liturgy, even if it seemed to work.
I would add that even good Southerners wouldn't use it, since they have tended to hold on to traditional liturgical English longer than those in other areas of the country. This may be because they just have good sense, or it may be because they are more naturally comfortable with Early Modern English because of its similarities to Southern speech cadences.
I'm afraid that the Yankees would be just as prejudiced toward the use of Southernese in the liturgy as apparently Latins were toward the use of Germanic languages.
P.S. Wasn't the Wulfilas Bible the product of the Gothic church in their Arian era? I'm not sure that the Western Patriarchate can even take credit for that. As so, historically, we are left with the curious oddity of the Indian languages in North America (but apparently not other non-Indo-European languages in, say, India or the far East.
Whoa...now a wait a minute here folks! LOL
Justly proud though ye may be in y'all, here in urban Yankee land (Philly, NJ, NYC, Boston), we invented the perfectly servicable plural "youse" = "Are youse going?". And out west just a little ways in Pittsburgh and the Appalachians, they have "y'uns"--Pittsburghers even call themselves "yinzers" it's so ubiquitous in their speech.
I just looked up Wulfilas and you're right--he was an Arian.
It is unfortunate that the career of Ulfilas was marred by his adherence to the Arian heresy. It may be said in extenuation of this fault that he was a victim of circumstances in coming under none but Arian and semi-Arian influences during his residence at Constantinople; but he persisted in the error until the end of his life. The lack of orthodoxy deprived the work of Ulfilas of permanent influence and wrought havoc among some of his Teutonic converts.Indeed, this article alleges that it was the translator's very Arianism that doomed it. Perhaps had he been orthodox, a Gothic church may well have emerged.
Pinging Antoninus, for his wisdom in things Gothic. Any thoughts?