That's really weird, as English is not a Latin language, and the Latin word "coquere" is very close from the English "cook". And it's not via the Old French.
From Middle English cook, from Old English cōc (“a cook”), from Latin coquus > (“cook”), from coquō, ultimately from Proto-Indo-European *pekʷ- (“to cook, become ripe”).
Spanish cocer, French cuire, Italian cuocere, rather directly from Vulgar Latin cocere
Cognate with Low German kokk (“cook”), Dutch kok (“cook”), German Koch (“cook”), Danish kok (“cook”), Norwegian kokk (“cook”), Swedish kock (“cook”), > Icelandic kokkur (“cook”), Spanish cocer.
It seems one of the rare exceptions, where an English word coming directly from a Latin word (and not being law or science jargon), not via the old French, or there's an old French word, that played the go-between, but that I'm not aware of.
In your quote from wiktionary it's mentioned the old proto-indo-european as the ultimate origin.
I think this is the one to be considered, as German, Dutch, Danish, etc., have a very similar word.
We all speak some kind of indoeuropean language, after "a bit" of evolution...
The Latin word, 'actor, actōris' is a more general term that comes from 'agō, agere, ēgi, actum', and has many meanings - shepherd, drover, agent, legal counsel or advocate, 'actor' (as we think of one), steward, bailiff, etc. - basically "someone who does something (on someone's behalf)". Whereas the word 'histriō, histriōnis', has a very specific meaning, that of a stage or theatre performer. I'm guessing that the Cambridge course chose to use the word that it did as it resembles the English word "actor", and hence it would be one less word for the student/reader to have to learn:)
Like in French "acteur" is an actor, but also someone who acts.
"Ne pas être spectateur, mais être acteur."
In English too, translated by "being an actor rather than an onlooker. "
The meaning of "playing a role" from "actor" is not there, but it's "acting", with the idea of "doing an action that changes things". (moving things)
Thank you for your explanation! Very useful. Gaffiot confirms that an actor can be a shepard, "someone who makes the herd moving". And it can be used for everything where someone makes something move.