Aircraft insurance can be very complex and confusing, especially for the pilot. It may depend on whether the pilot is defined as a ‘covered pilot’ (which means protected under the owner’s insurance policy). This often depends on whether the pilot is considered an employee or an independent contractor.
In the case of the 5Y-DKK accident, the airframe and its occupants were found completely burnt out and I don’t know of any official report of the cause (and sadly Inthink it’s unlikely there ever will be). The only mention on the French BEA website is : ‘From eye witness explanation, it appears that the aircraft just fell from the sky with no power, after initially having flown low for some distance’