Can medical arts be effective in treating chronic conditions? Or are they specialized to battlefield treatment?
Yes and No (but mostly No).
Disclaimer: medical arts are not something that they get into much, and I haven't read the most recent main story chapter which I think may have more details on this topic, so if I'm wrong please correct me.
Medical arts, like all arts, somewhat depend on the individual casting them.
Most medical arts can cure, like, bruises and that's it. They can keep you from getting tired in combat, but if you get injured you'll need actual medical attention.
Now, arts can be used to do things like close wounds and re-set bones, but only if the person casting them has a detailed grasp of the anatomical features involved (and practice in using their arts in that manner).
Sometimes you get people with arts that can do much more than this though. Nightingale and Mephisto both have limited medical knowledge and nevertheless have some of the most powerful healing arts we have seen. In specific regards to chronic conditions, Nightingale's arts have been shown to mitigate oripathy symptoms (albeit at the cost of her own health).
