Hi and welcome.
I know how hard the diagnosis process is and Cf can really be confusing. You've come to a great place to find answers while you wait fo rthe docs to return.
A borderline result means its neither clearly positive, nor clearly negative. My daughter had 2 borderline sweats, but later genetic testing revealed she does have CF. You will probably go the genetic testing route at this point so you can determine if your daughter has CF and if not, why her sweat tests are elevated. There are other things that can cause elevated sweat chlorides, but having pancreatic sufficiency with elevate sweat test probably makes the doctors quite suspicious about CF.
Good to hear that your daughter's lungs are doing well. Not all CF patients have lung issues right away, many develop them later on. From what I've seen around here, it seems like your daughter would be more likely to fit into some of the rarer CF genetic mutations...so please make sure that the doctors don't quit looking with a simple CF panel, which only looks for about 30 mutations. Ask if they will run a sequencing with deletions and duplication -- it will look at over 1500 mutations and is over 99% accurate.
Best of luck.