Its a big problem in every industry that uses them.
I would say that the marine side of things has more experence than the rest put together. And I know a couple of lads from sailing who have been pinched from boat yards to work on wind turbines etc.
But still to this day I believe that most repairs are in the hands of god and also the person that fixes it. The anal attention to detail of the fixer comes into play more than anything else. The same of course is the same with fixing metal structures but at least with them you can NDT them and carry out other checks to prove that they are fit for use.
Unlike the comporsite repairs where you have to trust that it has been carried out in exactly the right temprature, right humidity, there isn't any contamination of the matrix such as hairs or dust etc , the weave direction has been aligned exactly as per requirments (may need a full engineering analysis because it may be different to the original) Then you have issue with the interface between two matrixes and not actually knowing whats been damaged you can have sections where the fibre has gone but the matrix looks fine and you wouldn't have a clue.
I know I am an ex engineer that mainly worked with metal but the state of affairs when I stopped working as an engineer was that the compersite side of things was at the same level as pre liberty boats and the Comet with metal. You asked any of them if they could prove anything and they would start talking statistical proberbilitys of failure.
I know things have improved since then on the production side of things but the fixing them still isn't a science in the same way as fixing metal is.