Hi all potted out
I don’t know precisely what shimmies and frostlings are. But I assume from the context that they are supposed to be “spirits” or “witches” or “ghosts” or something similar. Something pagan and not religious.
A Google search for “frostling” produced a PC game that has a “Frost Witch” and “Frostlings”. If your sentence was written in the last few years, maybe the author got the word frostling from from the PC game.
Sometimes ghost’s appearance is described as “shimmery” or “shimmering”. So, maybe that’s where the word “shimmies” comes from. A “shimmy” might be a local name for a ghost.
Since the sentence includes the words “of local renown”, you might also assume that some of the names of things might only be known/used locally. I think the words “of local renown” refer not just to frostlings, but to all of the things mentioned.
In the context, I understand the word crooks to mean people who are “crooked” or who resort to trickery.
Sorry APO, that’s the best explanation I can give you.