How did the Hebrew “R” change from a rolled “R” to a French-like “R”?

The short answer is because most senior Israeli politicians in the 1950s through early ’70s (such as David Ben-Gurion, Menahem Begin, Shimon Peres, etc.) were foreign-born and couldn’t do the guttural rolling Rs, so used trilling Rs instead, as in their native Russian or Polish—whereas modern-day leaders are almost invariably native Israelis. (The exceptions were Golda Meir and Abba Eban, whose mother tongue was English, so they spoke with painfully Anglo-Saxon Rs.)

But as we say in Hebrew, בואו נעשה סדר בדברים—let’s clear up some things, as there’s a common confusion here, even among Israelis themselves.

Q&A: In Hebrew, if shamartem is “you guarded” (2nd person masc. plural) and shamroom is “they guarded them,” then what is “you guarded them” (2nd.masc.pl)?

This is a good question, as it highlights how Hebrew, in its love of concision by cramming prepositions and possessive indicators into the prefixes and suffixes of verbs and nouns, can sometimes overload itself.

As you partly point out in your question:

• “you guarded” (m.sing.): shamárta
• “you guarded” (m.plural): shamártem

Q&A: Has modern Hebrew changed grammatically or phonologically from when it was first revived?

Yes—quite a lot. The best illustration of this is the Hebrew of the first native speaker of modern Hebrew, Itamar Ben-Avi, son of Eliezer Ben-Yehuda, the ‘father’ of modern Hebrew and compiler of its first dictionary.

I recently read his autobiography (החצוף הארצישראלי ‘The Cheeky Hebrew Boy’), and although much of his Hebrew is not much different from high-register academic Hebrew today, some of it seems almost comically affected (although it wasn’t—that’s just the Hebrew he was brought up with). Typical example (not from his autobio, but from another project of his):

זה לי ארבעים שנה פחות ארבע, שאני הוגה בכתב העברי יומם ולילה ממש. מעודי לא יכולתי להבין מדוע לעברים אל״ף-בית כה קשה ומסובך, ולנוכרים – כה קל ונעים לשימוש? יום אחד – ואני אז בן-עשר – פניתי לאבי ואשאלנו: …״

Rough English equivalent:

’Tis four years shy of forty now that I have been contemplating the Hebrew script—yea, verily, day and night. Never have I been able to fathom why the Hebrews have such a difficult and convoluted alphabet, while the foreigners – [one] so easy and simple to use? One day – and I was but a lad of ten – I turned to my father and enquired of him:…

Q&A: What percentage of modern Hebrew vocabulary is native Semitic?

73.562.
Seriously, who’s measuring, and does it matter? What’s to say what’s “native Semitic”? Does that mean original Akkadian (the antecedent to Hebrew), or Northwestern Semitic/Canaanite which it became (and which itself had many foreign influences, from the Hittites and Sea Peoples as well as Egyptian)?

Do words such as Sanhedrin (from the Greek for “Council”), avir (air), cartis (card), téatron (theatre), itztadion (stadium)—all from Greek at least a thousand years before any modern European language began to emerge—count as “native”?.

Q&A: In Genesis 15:6, what nuance, if any, does the Hiphil/causative form of “believed” (וְהֶאֱמִין) indicate about the nature of Abram’s response to the divine promise of innumerable descendants?

It indicates the overcoming of natural scepticism. 

There is no plain-vanilla—i.e., pa’al—version of the root a-m-n. In other words, there is no verb le-émon לֶאֱמוֹן. Belief is something that needs to be applied to oneself—the default mode is disbelief. (As they say in Missouri—’Show me.’)

Similarly, there is no verb for ‘going far’: when one simply goes, one holekh—but when one goes far, one marḥiq lekhet—lit. ‘make distance going’.

So when Abraham is persuaded that God will do all that He is promising, he is actively overruling his natural scepticism, to make himself believe.

*

Q&A: In Hebrew, how is it possible to discern when to pronounce shva as /e/ or not at all?

For the sake of illustration, in this answer I shall represent the shva as a colon in the middle of the word (:). There are four rules for determining whether a shva is na (‘moving’) or naḥ (‘resting’):

Q&A: What is the difference between the Hebrew words dabar and amar?

The verb d-b-r (דבר) is to speak—i.e. it is more formal and intentional. Hence words put in writing are also dbrim* (‘dvarim’); the Ten Commandments in Hebrew are Aseret Hadibrot (The Ten Proclamations); and religious prophets always warned civic leaders to honour at hdbrim awr H’ xivh* etc. (the things that the Lord commanded).

Q&A: What is the meaning of the Hebrew proverb ”שמחת זקנתי בראש חוצות”?

It’s not a proverb so much as an expression of disdain or indifference. In common usage, only the first two words are used—with a suitable expression of boredom or nonchalance, while pointedly not looking away from whatever you’re doing at that moment: שמחת זקנתי… (Simhat zqenti…)

Literally, it means, ‘My old woman’s happiness for all to see’, and is a translation of the Ladino (Judaeo-Spanish) expression, La gracia di tu mana (‘Your mother’s happiness’)—i.e., ‘[That might make my mother happy, but] I couldn’t care less’.

Q&A: Why might a translator use a calque?

[A2A] One would use a calque (a.k.a. loan translation) when there is no equivalent word or expression in the target language, but it captures the meaning so well and concisely that it is recreated in the target language by emulating the same word combination with native words.

In Hebrew, noted examples are:

Q&A: Are the Yiddish and the Hebrew cursive scripts the same style?

Pretty much—since the modern Hebrew cursive (MHC) is based on the Ashkenazi cursive style that began to emerge in the 18th century, or thereabouts.

Here’s a fairly typical example of Yiddish handwriting: