I think Candace's lawyer's arguments revolved around that the elders did fulfill their duty of care towards Candace sufficiently. I think this came out when Candace Conti's lawyer questioned the elders regarding what safety measures they had put in place to prevent Kendrick from ever working in the field service with children. If this aspect is significantly important then surely it would not matter so much that Candace did not (and was not asked by her lawyer directly enough to) testify to being assigned to work with Kendrick?
I think you may be missing that there are two alternative theories of liability at play here: misfeasance and nonfeasance. What you are describing sounds like nonfeasance; that they didn't do enough to warn or protect her. You are correct that the attorneys do not have to show that they were assigned together in field service to prevail on that theory.
But Rick Simons also argued on appeal that even if there is no such duty, the verdict should be upheld due to misfeasance, and the only evidence he points to for that is the field service issue. I was only commenting that there had to be enough evidence at trial for a jury to conclude there was misfeasance for the judgement to be upheld on that basis.
Conti's team doesn't have to show a basis for both theories; only one. Since juries don't have to explain themselves, if the court finds one of the two theories viable under the law (and assuming the WT doesn't win on one of its other arguments) the jury verdict will stand, assuming that the jury accepted that basis.
I agree that it's sad that only the threat of legal liability works to force their hand to protect their children.