I'm thinking about the construction "ka pa," as in "Yo ka pa wè sa." I understand this to mean "They might not see that." Does that sound right? What I'm really wondering is how this same construction would be translated in the song that says, "Yo kapab pa janm tonbe, delivrans yo asire." Would this be "They are able to not ever fall," instead of "They might not ever fall?" Thanks again for all the help!

"Yo ka pa wè sa." (or Yo te ka pa wè sa.)
"They might not see that."
That sounds right.

"Yo kapab pa janm tonbe, delivrans yo asire."
Your second translation captures it "They might not ever fall, their salvation is certain."

Putting it into context from the Creole song......
People who put in Jesus an immeasurable trust
They might not ever fall, their salvation is certain

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words