It's a good thing you have a great CAV, that's extremely important...
The good news here is that her tail-feathers are growing back-in in the first place, that's a good sign...So based on the fact that the tail-feathers are continually growing back-in after being pulled should most-likely rule-out any problems or diseases/conditions with the actual feather-follicles, and that's a very important factor when it comes to PBFD...
****Something that I'm not clear on....Are you actually seeing her breaking the tail feathers, or are you simply finding her with them already broken? This is an extremely important distinction, because if you are certain that she's constantly breaking her tail-feathers by crashing while flying or landing hard/crash landing, then this isn't at all a feather issue, it's actually either a physical medical issue or a Neurological issue, most likely due to either #1) Not being allowed to fully-fledge properly by her breeder (this would only be applicable if she's been a "bad' flier since the day you brought her home and her inability to fly isn't something that developed well after you you brought her home and she was actually flying normally and not crashing at first), OR #2) She has an underlying medical issue that is causing her to suffer from a Neurological issue or a medical issue that is directly effecting her ability to fly/balance/fly with control; these include a few different Avian Viral Diseases such a PDD, PBFD, ABV, Polyoma, etc. As far as physical medical issues that can cause a bird to not be able to control their flying or landing, they include everything from a middle or inner ear infection, an air sac issue, or even an issue that is effecting her legs or spine, such as a Sciatic Nerve issue...
This really depends on when her ability to fly with control and land properly first started...If she was NEVER able to fly with control or land properly, then you may be looking at a Neurological issue caused by improper fledging or abundance weaning. If it's something that started well after you first brought her home, then you worry about the physical-medical issues and/or the Neurological symptoms of certain Avian Disease processes, such as the Viral Diseases, certain Bacterial infections such as Avian Hepatitis, Avian Tuberculosis, Avian Thyroid issues, or simply a horrible inner ear infection.
****If you are NOT seeing what is causing her tail feathers to break, meaning you're not seeing her crash while flying but she's suddenly just appearing with broken tail-feathers, this is often caused by their cage being too small for them or having too many toys/objects inside and as a result they are constantly banging/rubbing their tail feathers on the cage bars (this is quite common), OR it could also be due to her having "Night Frights" as you mentioned...If she has frequent Night-Frights they can certainly result in broken tail-feathers.
When you take her to your CAV, you definitely want her to have a Fecal Culture sent out and for them to do Microscopy/Gram-Staining in the office to look for Bacterial, Fungal/Yeast, Protozoan, Parasitic causes...Then you also want to have full, routine Blood-Work done, as well as added, individual tests for PBFD and PDD, and any other individual tests that your CAV recommends or thinks might be applicable. I would also HIGHLY RECOMMEND that you request that they do a set of regular X-Rays. Some Avian Vets will suggest taking plain-film X-Rays right away in these types of situations, some don't, but the bottom-line is that in my experience when they don't do any X-Rays on the bird during the first appointment in situations like this, they end-up running the Fecal and Blood Tests, and they send the bird home to wait for the results, sometimes they put them on medications "just in case", such as Antibiotics, which is not good practice until they've done all the basic tests to rule-out every common cause, and then you'll end-up just having to bring your bird back in again for another appointment to have them take X-Rays if the Blood-Work and Fecal tests don't give any answers...And that means another visit where your bird is put under gas-sedation once again and is highly stressed once again...It's much, much, much better for your bird and for you and your own stress over the situation if you request that your CAV do ALL of the basic tests all at the same time during the first appointment. They have to use a very short-acting sedation to take X-Rays of a bird, either Isoflurene Gas (most common) or short-acting Nasal sedation, so it makes much more sense to save your bird added stress, a second visit, etc., and simply do their physical exam and history in the exam room with you, and then simply put your bird under short-acting sedation ONLY ONCE and take the Blood and the X-Rays at the same time, so that your bird gets everything done at once, wakes-up, and is good to go. Regular X-Rays are going to confirm or rule-out an inner ear infection, an Air Sac issue, any masses/growths/tumors, such as a Thyroid tumor or a mass in the cranium, such as a Pituitary tumor, any metal that the bird may have ingested that has been sitting in his Crop/Stomach/GI Tract and is causing Heavy-Metal Poisoning, etc. Bottom-line is you'll get a hell of a lot more answers with both Blood-Work and X-Rays, and better to do them all at one time than to keep having to bring the bird back in and putting them under sedation over and over again...
