Well, I asked my question about how do words' origin helps in making spellings and not whether the contestant heard the spelling properly. If anyone watches that series' videos (or videos of that category), they'll know that in the latter case, contestants asked the quiz-master -could you pronounce it again? or Can you repeat the word please?
Learning etymology also helps in constructing words as mentioned here.
You will be able to construct many English words correctly by learning to put these building blocks together in the proper way.
So again, I am concerned about assuming the spelling on the basis of their origin. Here is what I found which I think is useful for me and others to learn about it. I'm pasting it in-situ so that I don't miss anything from this useful piece of information. The source says the tips are from Merriam-Webster.
Note: As I mentioned in my question, this may not be the complete guide but certainly helpful as a part of the answer. I also learned that after having known the origin of the word, it has to be checked with its pronunciation to guess a perfect spelling. Because these tips first teach about how words' are spelled based on their Latin and Greek origin but after correlating them with their (nuance of?) pronunciations.
Spelling tips for Latin based words
"One of the hardest things to remember about words from Latin is whether an internal consonant (like rr in interrupt) is doubled. To reinforce your memory of the correct spelling, try to remember related words all together (like interrupt along with interruption or necessary along with necessity)."
"The \ü\ sound (as in ooze) is nearly always spelled with u in words from Latin. It typically follows a \d\, \j\, \l\, \r\, or \s\ sound. After other consonants, this sound normally becomes \yü\ (as in bugle, subterfuge, ambiguity, and prosecute and in one pronunciation of refugee)."
"Beware of words like crescent in which the \s\ sound is spelled with sc in words from Latin. Other examples include visceral, discern, discipline, susceptible, and corpuscle."
"A related tip: When you hear within a word from Latin the \s\ sound followed by any of the sounds of e (long, short, or schwa), there’s a possibility that the \s\ sound is spelled with c as in exacerbate, access, adjacent, condolences, facetious, and necessary."
"The letter i is a vowel often used to connect two Latin word elements. If the connecting vowel sound is a schwa (\ə) and you must guess at the spelling of this sound, the letter i might be a good guess: See carnivore and herbivore. Other examples include non–study-list words that end in iform such as oviform and pediform."
"The letter k rarely appears in words from Latin, and its sound is nearly always represented by c as in canary, prosaic, canine, mediocre, Capricorn, cognition, ductile, incorruptible, vernacular, innocuous, and many other words on the list."
"The letter x often gets the pronunciation \gz\ in words from Latin (as in exacerbate and exuberant)."
"The combination ious ends many adjectives of Latin origin. When the consonant that precedes ious is c or t, the sound of the final syllable is \shəs\ as in precocious, facetious, ostentatious, and pernicious. It is important to keep in mind that several adjectives from Latin ending with this sound end in eous rather than ious. In such instances, the definitions of the words usually contain phrases such as “consisting of,” “resembling,” or “having the characteristic of.” Examples include non–studylist words herbaceous, cetaceous, and lilaceous."
Spelling tips for Greek based words
"In a few words from Greek, e appears at the end of a word and has long e sound \ē\: Some examples are acme, apostrophe, and hyperbole."
"A \k\ sound in English often represents a sound from Greek that we don't actually use, and the most common spelling of this sound in English is ch: See anachronism, arachnid, character, chronic, chronology, dichotomy, hierarchy, matriarch, melancholy, patriarch, synchronous, notochord, tachometer, and gynarchy."
"The most frequent sound that y gets in words from Greek is short i (\i) as in acronym, calypso, cryptic, cynical, dyslexia, eponym, homonym, myriad, Olympian, synchronous, synergy, synonym, synopsis, syntax, symbiosis and polymer."
"A long i sound (\ī) in a word that comes from Greek is sometimes represented by y, especially after h, as in hydraulic, hydrology, hygiene, hyperbole, hyphen, hypothesis, dynamic, cynosure, gynarchy, xylophone and pyre."
"In ancient Greek, the letter phi (pronounced \fī) represented a breathy or "aspirated" version of the sound that is represented in English by f. Speakers of Roman-alphabet languages did not have this sound or a corresponding letter, so they substituted the \f\ sound but memorialized the original sound of phi by using ph to spell it. As a result, the English \f\ sound almost always appears as ph in words of Greek origin. Consider, for example: amphibious, apostrophe, cacophony, diphthong, epiphany, euphemism, hyphen, metamorphosis, metaphor, periphery, phenomenon, philanthropy, philately, philhellenism, spherical, topography, xylophone, and zephyr. Hundreds of words in English derived from Greek show this spelling."
"The letter o is the vowel most often used to connect two Greek word elements. If the connecting vowel sound is a schwa (\ə) as in xylophone, notochord, orthodox, ergonomic, geoponics, and asthmogenic and you must guess at the spelling of this sound, the letter o is a very good guess. The non–study-list words hypnotist, geometric, and electrolyte are among the many, many words made of Greek word elements connected by o."
"The \j\ sound is always spelled with g in words from Greek. Why? When the \j\ sound appears in words of Greek origin, it does so as an anglicized pronunciation of a root originally pronounced with a hard g. Note that no j appears in any of the words on this list!"
"A schwa in words from Greek is occasionally spelled with y: See analysis, etymology, misogynist, odyssey, and zephyr."
[I disagree with Jonathan Garber over his answer as much as I agree with him over his comment! Because in comment, he really got what I asked but while exploring the answer, (probably) he felt heading somewhere else and deleted it. I firmly believe that that answer of him was very likely to get good responses by learned users here as healthy talks in their comments. Probably hunter would agree on this. Never mind, I thank him for whatever input he gave. It is very useful.]