As Bones writes, the M&M series has some long traditions, including the "ancient technology" that turns out to be our RL future tech. There's an actual Lloyd (hence the Beacon's name) and a town of Sorpigal somewhere along the way. I always thought the Evil Churches being named after animal sounds was a semi-homage to The Nights Who Say Ni (even though that's just a very funny sound, not an animal noise).
So I've always assumed that "Baa" was pronounced like Americans & Brits imitate a sheep's bleat (the jargon word for the noise),
Wiktionary says:
(UK) IPA: [bɑː]
(US) IPA: [bæ], [bɑ]
(However, I know that Americans pronounce that sound differently, depending on the region — I assume there's even more variation across the UK & Ireland).
Not sure if I trust wiktionary's translations, since it links to synonyms in other languages for the "bah" sound (e.g. Scrooge's "bah, humbug"), not the animal sounds.
Finally: Hi, Peter!