The pseudo-archaic English is an acute agony—a cursed hybrid jargon belonging to no age at all! That’s Hodgson’s weakness—you’ll not a sort of burlesque Elizabethan speech supposed to be of the 18th century in “Glen Carrig”. Why the hell can’t people pick the right archaic speech if they’re going to be archaic?

— H. P. Lovecraft to August Derleth, 6 Nov 1934, Essential Solitude 2.664

Hope both you & Æmilius will enjoy “The Night Land” et al. This novel has grave drawbacks—an almost insanely absurd attempt to reproduce archaic (presumably XVII cent.) English which resembles no English ever spoken or written on this planet; occasional touches of sickening sentimentality; & a verboseness which gravely taxes the reader’s patience—but for all that is a stupendous piece of imagination. It was Hodgson’s own favourite among his works, although I believe “The House on the Borderland” averages better.

— H. P. Lovecraft to Duane W. Rimel, 18 May 1936, Letters to F. Lee Baldwin &c. 321

The use of improper archaic English was a personal pet peeve of Lovecraft's, who was otherwise very fond of Hodgson's weird fiction, and the sort of mistake that quite a lot of writers have made over time. Typical sources for what "old-timey" English speech sounds like are typically widely-available works like the King James Bible (1611), the collected works of Shakespeare (written in mostly in the early 1600s and collected in the first folio in 1623), and popular novels of later eras such as John Bunyan's Pilgrim's Progress (1678) and Daniel Dafoe's Moll Flanders (1722) - however, all of these sources have their own rhetorical flourishes; people didn't speak colloquially in the poetic feet of Shakespeare's plays, or with the deliberate archaisms of the King James' Old Testament, any more than the typical inhabitant of the American colonies spoke in the style of the Declaration of Independence (1776). While Hodgson might have been borrowing individual elements from some of these sources, it is much more likely that he was really borrowing from Gothic novels which were themselves faking 17th and 18th century prose. So to give an example of the archaic text involved in The Night Land:

Now I eat and drank at the sixth and the twelfth hours, and went onward at a very strong speed. And at the sixteenth hour, I did seem as that I knew the aether to be stirred about me, and the beat of the Master-Word very faint upon mine inward ear. And immediately, a wondrous great and lovely thrilling did wake all my being; for surely, I said, this was the spirit of my love, calling unto me with her brain-elements. And, indeed, this was a very proper and sensible thinking; for had the Master-Word been sent from the Mighty Pyramid, I had been like to hear it very plain, by reason of the force of the Earth-Current which was with them and to their command. But, as you do know, the Earth-Current was nigh gone from the Peoples of the Lesser Refuge; so that they were over-weak to make any proper calling. And this I have spoken of before this place.

Deliberate archaisms here include the use of "XXth hour" instead of the contemporary "X o'clock"; the use of conjunctions (And, But, etc.) to begin sentences, the capitalization of selected nouns as if they were proper nouns, selected hyphenation to suggest more complicated conjunctions ("brain-elements"), and elsewhere the selected use of deliberately "archaic" words (hath, thiswise, thee, thou, thine, etc.)

By comparison, here is a chunk of Moll Flanders:

But now I found the thing too far gone to conceal it much longer, and my husband himself gave me an opportunity to ease myself of the secret, much to my satisfaction. He had laboured with me three or four weeks, but to no purpose, only to tell him whether I had spoken these words only as the effect of my passion, to put him in a passion, or whether there was anything of truth in the bottom of them. But I continued inflexible, and would explain nothing, unless he would first consent to my going to England, which he would never do, he said, while he lived; on the other hand, I said it was in my power to make him willing when I pleased—nay, to make him entreat me to go; and this increased his curiosity, and made him importunate to the highest degree, but it was all to no purpose.

Dafoe does occasionally begin a paragraph, as here, with a conjunction, and the text, as with The Night Land is in the first person. But Dafoe also uses "o'clock," varies the structure of the paragraphs and sentences considerably, uses contemporary colloquial language, etc. Many of the individual elements of Hodgson's pseudo-17th century speech are present, but not anywhere in the same profusion or in combination with all the other elements.

It is a lot like comparing a bad contemporary television program, that uses whatever they think of as elements of medieval life, culture, and speech without thinking about how they go together or with any understanding of what people in that period would really have looked and sounded like.