The "rough" feathering appears to be what is called squirrel feathering which can be common in lavs that are breed lav to lav without splitting back to black. The good news is you would improve both feather quality and lavender color by adding a black to the lav. You would then be able to breed the black/lav babies to get a better quality. The birds are also at that teenage age where they can look a bit scruffy before they get their adult plumage.
Looking up close though the feathers are very squirreled. Good luck.