"The Phoen. adaptation of the alphabet was extremely successful..." is not the full truth. In fact, it was the ONLY AVAILABLE script that had survived the Sea Peoples' devastations. The oldest Aramaic ´still had MORE than 22 phonemes, Olkd Hebrew still had ghain and s´în apart in speech - but they lacked an extra letter to express them.
"Old Italic" should be specified - I think it was only Messapic; anycase the Etruscan alphabet came from the Greek city Cumae.
The Chapter Letter names bases on pure speculation. And NOELDEKE's approach is noe 108 years old ...!
"One of these local Greek..." - why not NAME it? It was the variant from Miletus, adopted in 403 BCE to Athens; the other was the alphabet of Khalkis in Euboea which wandered from the Greek city of Cumae to the Etruscans.