Mine is 2006 #125. I do not recognize the area you show, where is it ? You should remove the
gangway floor to get a better understanding of how your
boat is built.
Two half hulls (lengthwise) are joined together, the keel is part of it. That forms an hollow keel. An inner keel mould is then inserted/glued in there (obviously from the inside) with lots of mastic. That clean white gelcoated inside mould is what you will see when removing the floor.
There could be some water in between the actual hull and inside mould, if the
boat was grounded and quickly/badly repaired for example.
Did the expert do some moisture test ?