I'll add: Yitshak become Tsahi, Yehezkel - Hezi, Yehoram - Rami, Yonatan - Nati
Jeffrey comes from Ephraim. Weren't YOU called at home Frojm, (or smthng like)?
It is natural in every language to shorten the names at home.
I'm sure Ivanka doesn't call her husband (at home) Donald, but ... i don't know English well enough...
I am sure that italian woman in Israel would be called Tali.
I tryed to answer your question.
Some linguist would do it wider...