How has modern "Halloween" influenced the neo-Medieval's view of the superstitious villagers who came up with legends to begin with? Especially after a century of codification and then subversion?
Vampires have certainly undergone different permutations from ghastly to sexy, but nowadays they definitely take the most cues from Dracula, as sort of the landed class of monsters. Their classic Hollywood weaknesses like crucifixes, garlic, and sunlight are brought up, and while most Europeans have forgotten turning into a bat lore, the New World vampire bat figures greatly into their legends. The story of Dracula is very popular, due to the character's ubiquity, and that an honest-to-God Texan features in the original novel!
The humanoid, bipedal werewolf is more common than the "just turns into a wolf" type, and very interestingly, "werewolf" is more or less synonymous with a local translation for "beast".
The kingdom of New Mexico did their best to emulate Ancient Egypt (and to a certain extent, the great pre-Columbian empires), which includes God emperors, pyramids, and of course mummification. For their part, Easterners like to spin yarns of explorers venturing into the deserts and coming across Mummy cults. On the one hand, this has the positive effect of discouraging the idea of defiling the tombs of indigenous folks, but on the other, they're somewhat put off by more sanitary embalming methods.
Unlike a lot of monsters, Frankenstein's monster is not really a "species" per se, but his legend has captivated people for generations, especially since the story resonates in a world that vaguely knows mankind paid some kind of price for growing too proud. The story of Frankenstein probably encourages a Luddite sensibility in the population, almost a polar opposite to witchcraft.
The concept of the "Witch Hunt" is a pejorative in American culture, but in a reversion, people are going to go back to the superstitious ways. Especially since even modern Americans seem to have the meaning of a witch hunt backwards. New England probably resembles its colonial era more than any other region, so hysteria is going to happen. For its part, the top brass Non-Denominational Church denies the existence of witches, but The United States needs some kind of justification for warring against the Voodoo practitioners of the Secretarial States...Some retelling of TheWizard of Oz explain away Glinda as more of a "fairy" then a witch.
Showbiz folk are not trusted in the more God-fearing Medieval America, and doubly so as, in the new Middle Ages, performers are more likely to wear a face-covering mask than mere makeup. In fact, in some languages, "clown" basically translates to "colorful, disguised brigand" more than "Jolly entertainer".
Once upon a time, "Cowboy" was considered as American as something gets, but now they have an unsavory reputation as barbaric apostates. Their raids and foreign religion have certainly not endeared them to the Midwesterner, but the red-state vs blue state mentality of the Northeast, and the South being almost completely composed of those we would consider "people of color"has given the East a sort of bad "ancestral memory" of those who don the cowboy hat.