Watching this as my '16 has mystery water leak too. Sometimes water is filled in the second row seat bolt wells, the last time things got wet was underneath the right second row passenger seat only the carpet. Just a lowly XLT... No sunroof, heated/cooled seats etc. My '04 had a mystery leak on the driver's side near the A post recently, I checked and reglued the weather seal on the door frame and that seamed to stop it. On the '16 the water inside seems to only happen with a windstorm and rain so I suspect perhaps door seal s well but don't see any issues.