[A2A] I haven’t seen any hard evidence of this in the literature, but I would imagine that this has always been the case.
When I say ‘always’, bear in mind that originally (i.e. in Canaanite Hebrew script that reigned until the return of the end of the First Temple period, ca. 585 BCE), and even in the first thousand years of the use of Assyrian script for Hebrew in the Second Temple period (ca. 525– BCE), there were no modified sophit (end-of-words) versions of the letters kaf-mem-nun-peh-tzadi—as evident in this example (of the word maḥatz) from the Dead Sea Scrolls of ca. the start of the Common Era:
The invention of sophit versions emerged as a stylistic flourish only in the middle medieval period (certainly by the time of the Aleppo Codex of the 10th century CE) to emphasise that no letter followed them in the word. Since the f-sounding peh sophittypically occurred only in proper Hebrew words, naturally, if any foreign word or name was spelt, they would have deliberately kept the non-sophit version, to emphasise that the final letter is p-sounding, rather than f-sounding. But there was no consistency on this point, because the rules of Hebrew apply only to Hebrew words and names—when it comes to foreign terms, people can, and do, improvise.
A related, and no less interesting question, to my mind, is why do Israelis resist using the peh sophit to indicate an f-sounding peh at the start or middle of words. When I launched my Hebrew-language blog Al-Fadiḥ about a decade ago, I naturally spelled the title אל פדיח, and it took me a full five years before I could overcome the deeply-ingrained cultural resistance to using a peh sophit to indicate the f-sounding peh at the beginning of the second word.
The title of the blog is a play on the word fadiḥah, which is an Arabic word for ‘embarrassing error’, or ‘boo-boo’, and since the rules of Hebrew apply only to Hebrew words and names—it dawned on me, why can’t one use a peh sophit to indicate the f-sounding peh at the start of the second word? There is no reason—and yet I had to summon up every ounce of my iconoclastic tendencies to bring myself to do so, if only as a graphic illustration of a mistake:
Having overcome that mental block once, I’ve since used it often in my blog posts and correspondence with clients when transliterating foreign words and names in Hebrew—and they understand what I’m doing, but not one of them has yet allowed themselves to emulate me as yet. This may change, but it will take some time. Tradition is like gravity—it’s hard to break away from it.