How to pronounce things

[Rankin, Robert L]

>  I stand corrected on Chitimacha. Seems I've been saying it wrong all these
years. But surely the second ch is sh.

I strongly suspect they both are/were and that the affricate pronunciation is a spelling pronunciation attributable to taboo avoidance.  Who wants to stand in front of a class of late teens and say "shitty" right out loud?  It would sort of make it an "unteachable moment."
 
Bob