<<How do you only get 3 syllables out of "panacea"?>>
If your dialect experiences what's known as "smoothing" of underlying separate vowels to diphthongs. Think of a traditional upper-class RP accent and how "here" is pronounced. That diphthong (with the schwa on the end, so [hI@]) obviously has two vowel components since it's a diphthong but the word is still one syllable since diphthongs inherently don't take up two syllable spots (think of the word "light" with its diphthong [aI] yet it's still just a one-syllable word). Anyway, the idea of smoothing in such situations has always seemed like a somewhat exotic idea to me--for the words listed above I always have the higher amount of syllables than the lower (but that's not a big surprise considering my dialect).
If your dialect experiences what's known as "smoothing" of underlying separate vowels to diphthongs. Think of a traditional upper-class RP accent and how "here" is pronounced. That diphthong (with the schwa on the end, so [hI@]) obviously has two vowel components since it's a diphthong but the word is still one syllable since diphthongs inherently don't take up two syllable spots (think of the word "light" with its diphthong [aI] yet it's still just a one-syllable word). Anyway, the idea of smoothing in such situations has always seemed like a somewhat exotic idea to me--for the words listed above I always have the higher amount of syllables than the lower (but that's not a big surprise considering my dialect).