Hello folks,
tried to clean up the model by using Meshlab's "removal of duplicated face", "removal of isolated faces" and some more of those nice filters (there's one that allows for completely removal of edge splitting: "merge adjacent vertices"
). Well, the results were mixed because if a mixture of defects. In the end, I noticed much manual clean-up is still required ... as Wise already pointed out, the model's state "is a nightmare".
Gap, good luck ...