Complex sentence: It claim was that the artifact dated back to the 14th or 13th century B.C. but that the inscription is a modern forgery with its apologies, and Professor Aaron Demski admits there is an 80 percent certainty that the inscription is a forgery.
Split into simpler sentences: It claim was that the artifact dated back to the 14th or 13th century B.C. however the inscription is a modern forgery. It was claimed by Professor Aaron Demski that there is an 80 percent certainty that the inscription is a forgery.