A helpful word for any who need it: (Anglicanorum) Coetibus is pronounced, in the Italianate 'Ecclesiastical' pronunciation, Chay-ti-buss. This is because (diphthongised) o+e=e; which 'softens' a c.
If you are Ciceronians or Erasmians or whatever, I suppose you say Koy-ti-buss.
In the old-style English pronunciation of Latin, it would be See-ti-buss.
Not Ko-eet-i-buss or Cho-eet-i-buss. Coetus and Coitus are distinct words, although, entertainingly, they do share a common ancestry.