My "Salambo" comes from Roger Abrahams (Deep the Water).

In North Indian languages, "s" often swaps with "sh". I don't know if that makes them allophones, or if it was a sound shift (older sh > newer s) or what. Not sure how that might be relevant, just responding to the prompt :)

I don't know anything formal about Caribbean. One anecdotal example that comes to mind is how Jamaicans say "Irish moss." They say "maash."
Also: d > g in "fiddle" > "figgle"; t > k in "little" > "likkle".

The "S- paradigm" I'm thinking about has three syllables. It could be proposed: Syllable 1 starts with s/sh (fricative), syllable 2 starts with n/l, syllable three is a stop (d/b?). Not trying to over-theorize it. But when I am producing (through singing) "Shannadoh", "Shallow Brown," etc., what's in my mind is a rough blurry category with these characteristics. It's like how "do re mi" can also be "mi fa sol" as a pattern. As an improvising musician, in my musical language, these two things are somewhat like "allophones" to me. John Blacking (Irish ethnomusicologist) wrote about such paradigms of verbal/musical expression in Venda people's (South Africa) music back in the 70s when the "transformational linguistics" stuff was popular.