In addition, the sentences are very simple, no complex words, nothing unexpected. We can often understand something like, "it's time for lunch now" without understanding more usual sentences that contain names or terms. I, too, "passed" the hearing test for a CI--i.e., I hear "too well" for one even though even casual conversation can be challenging. I know that I guess about half of what I hear, and you can't turn that fine skill off during a hearing test! When the sentences are really simple, there are no distractions (sound or otherwise), in the isolation of a booth you can understand much better than you can in real life. Even in casual settings, someone suddenly introduces a new line of thought, and you struggle until you understand what the topic is.

I fully agree with your statement on knowing the words and statements in the hearing tests can skew the test results. Were you tested with the series of nonsense sentences? It's not like "The dog chased the cat and the boy hit the ball". They don't make sense, so are pretty hard to memorize. The SPIN (SPeech in Noise) test is also a must. It starts out with sentences spoken in quiet, and gradually increases the noise. Needless to say it's a test that is a bit stressful. Were you tested at a cochlear implant center? New research literature on cochlear implants suggests that people who would benefit from them are not being referred as they should be.