. Structures change; new words arise (nothing wrong with "impactful;" it conveys its meaning in a way that no other word has before it);
...
I'll have to disagree with that. Consider:
"The new zoning regulations impacted the neighborhood. The regulations were impactful."
compared to:
"The new zoning regulations affected the neighborhood. The regulations were consequential."
Or perhaps: significant, pivotal, meaningful - whichever might express the concept better. "Impactful" does not really describe anything to me. Whenever I hear "impactful", I envision a meteor or other object striking the subject. Perhaps a Tesla on autopilot.
Since I and my father's side of the family are Hungarian and my mother's side is Syrian, I became interested in languages at an early age. My first job was translating Russian in scientific journals. Sometimes I still do translation work, though by profession I'm an engineer (it pays much better). However, as you, I became highly interested in linguistics - certainly as much as photography. Besides Russian, I've focused on Icelandic, Norwegian, and German. My library of books on languages and linguistics far exceeds any books I have on photography or photographic equipment.
...
It should be noted that much of formal English grammar is based on Latin, and not on English. ...
The study of Latin and Greek certainly had and still has prestige in academia and influenced how linguists viewed languages. Certainly such things as "don't end a sentence with a preposition" or "don't split an infinitive" came from prescriptive "grammarians" using Latin as a model - where such constructs weren't done or could not be done. But ending sentences with a preposition or splitting an infinitive do exist in Germanic languages.
I will be simplifying greatly here, but the foundation of English - its grammar as well as words that are closest to our everyday existence, such as
house, land, hand, finger, this, that,... come from the Germanic branch. One need only compare the most common fundamental words and grammatical constructs in English to their German, Danish, Swedish, or Norwegian equivalents to see the family lineage (or compare Old English with Old Norse).
Only after the 1066 Norman Conquest did English begin to adopt Latin derived words for more abstract concepts (like "abstract" and "concept"), as the conquerors controlled government and laws, their language came with them and mixed with English.
Again to see English as being in the Germanic family, consider the English "He writes a book, he wrote a book, he
has written a book. He
had written a book."
In particular, note the present perfect and past perfect tenses being formed by the use of "has" and "had".
In Norwegian we have the exact same thing:
"Han skriver en bok. Han skrev en bok. Han
har skrevet en bok. Han
hadde skrevet en bok."
German has the same paradigm for present and past perfect, using
hat and
hatte.
The Latin equivalent of those sentences won't use an auxiliary verb as part of indicating tense - instead, tense is indicated entirely by conjugation from the verb stem.