So sorry to hear of your situation. I can sympathize because I had a similar situation earlier this year. After being launched by the yard, out boat partially sank at the dock overnight. it turned out that the yard foreman had failed to notice that there were sea cocks under the sink in the head, and one of the sea cocks was open with no hose attached. It stinks.
But the yard immediately contacted me; I was a couple of hours from the boat and unable to get there immediately, but they immediately hauled the boat, pickled the engine, dewatered her with pumps and accepted full responsibility. They also removed anything that might hold water or dampness, installed a dehumidifier on board and kept fans running to dry out the boat for more than a week. I did contact my insurance company, Boat US, who immediately assigned a contact person and within a couple of days sent a surveyor to inspect the damage. We did a survey of the boat with the yard owner, myself, the surveyor provided by my insurance company and one provided by the yard's insurance company. Both surveyors seemed to go out of their way to make sure that anything in any doubt was to be completely replaced, especially all of the electrical doohickeys, such as VHF, stereo, wiring panels, wires, alternator, starter, batteries, etc. They replaced everything soft on the boat (mattresses, cushions, etc.). Since the boat had been in winter storage, much was not on the boat, such as the chartplotter and sails, and so was not affected. Fortunately, the pickling of the engine seems to have worked and they ran multiple oil changes through it and the analysis of the oil and fuel has been fine.
After the joint survey, I spoke to the surveyor from my insurance company in confidence and he said that the yard was quite responsible. Unfortunately, in his experience, there are many yards that would have simply reconnected the hose or closed the seacock, and then said the cause of the sinking was unknown. Makes one wonder about the "unknown" origin of your sinking.
In my case, my insurance paid nothing, I paid no deductible, the yard and yard's insurance covered everything, and we got relaunched about 2 months later (though there were a few parts that came in later). The boat is, I suppose, at least as good as it was before the sinking, since it now has some updated electronics, new batteries, and other electrical, new cushions and covers, and seems to show no ill effects. I was quite concerned about mildew or smell, but the efforts of the yard seem to have solved that; I was also concerned that some of the floor boards or cabin liners might have ill effects, but I have seen none.
I hope your ending is as happy as mine, but I would be quite concerned about the insurance company's silence. BoatUS was on top of it almost instantly, before there was any discussion of cause or cure, and the quick work on the boat surely reduced the loss dramatically.