This is something authors do and it's something you have to accept and not try to work out reason behind it; or better yet you should learn to enjoy how clever they are! As I noted in a comment there are many examples besides Fenrir Greyback and Remus Lupin. Some of these include Bellatrix, Sirius Black (plus his father being Orion is relevant wrt Sirius), Lily and Petunia (yes!) as well as Harry himself. There are more. Pottermore covers many of them.
I'll list many examples.
Let's start with https://www.pottermore.com/features/dark-etymology-behind-the-black-family-tree
Another name for Sirius is the, wait for it… Dog Star. How fabulously apt is that? The etymology of the word Sirius as a dog is one which is carried across numerous cultures, all seeing him as a protector and a watchman, and each of these ticks the box that made up this remarkable wizarding hero.
That link has several others: Regulus, Bellatrix and Narcissa. What about Orion? If you understand Sirius is the Dog Star then you find out where that star actually is you have the answer. For instance from https://stories.barkpost.com/dogs-in-the-sky-canine-constellations/
you have (Canis Major is the Dog Star which is also known as Sirius):
There are many tales associated with Canis Major, commonly known as one of a pair of dogs helping Orion the Hunter to pursue Taurus the Bull. Canis Major is also depicted as chasing the hare Lepus across the sky.
But what about the Weasleys? https://www.pottermore.com/features/revealing-etymology-of-the-weasley-family-tree
That has several of the Weasleys listed:
Let’s look at ‘Ronald’ first: quite a common male name that has its roots in Old Norse language, from the name ‘Rognvald’. Rognvald, or Ragnvald, was the name of many old kings – giving a whole new meaning to Malfoy’s ‘Weasley is Our King’ chant.
‘Bilius’ has its origins in ‘bilious’, with bile making up two of the four humours – the bodily fluids that Ancient Greeks thought controlled a person’s health and temperament. Bile was said to indicate anger and melancholy, and Ron was definitely guilty of having a temper, especially when he got a bit jealous of Harry or his siblings.
It doesn’t take a great stretch of the imagination to figure out what ‘Weasley’ means. Weasels traditionally tend to be pretty sly and deceitful, but we’d wager this wasn’t supposed to suggest the Weasley family are in any way devious, but rather that the weasel’s bad reputation is undeserved. It’s also no coincidence, of course, that weasels live in a burrow… as do the Weasleys.
It also has: Ginny, Molly, Arthur, Bill, Percy, Charlie, Fred and George.
Or professor names: https://www.pottermore.com/features/etymology-of-hogwarts-professor-names
It has Flitwick, Trelawney, Slughorn, Grubby-Plank and Sprout and I think the Sprout is a more than obvious: she teaches herbology.
Some I've noticed on my own: Septimus Vector teaches arithmancy which is all about numbers; vector is from maths and septimus refers to seven the most magical number. What about Herpo the Foul? Herpetology mean anything to you? Study of reptiles. And what was Herpo the Foul known for? Hatching a Basilisk for example. I'll also point out that - though I'm not suggesting allegory I am pointing out the circumstance - the Second World War began on 1 September 1939; the fall of Berlin would be 2 May 1945 (and Nazi Germany on a whole would surrender and V-E Day would become 8 May 1945). But the Second Wizarding War began (you might say: the day school started) 1 September 1997 and ended on 2 May 1998.
Lily and Petunia? https://www.pottermore.com/features/lily-potter-petunia-and-the-language-of-flowers
The Victorian language of flowers was used back in the 1800s to send meaningful messages, convey deep secrets and share moments. Nearly every flower has a special meaning and, in times when some words could not be spoken aloud, bouquets would say a 1,000 words.
Asphodel and wormwood
If his first words to Harry are anything to go by, the language of flowers suggests that Snape deeply regrets Lily Potter’s death.
Asphodel is a type of lily and means ‘remembered beyond the tomb’ or ‘my regrets follow you to the grave’ while wormwood is often associated with regret or bitterness.
A lily can be interpreted as ‘beauty, elegance, sweetness’. This striking flower is easy to grow, as long as it is planted in the right place. They also, according to gardening manuals, make wonderful cut flowers.
Enter Severus; his name can be seen to mean to cut or to sever - and this is exactly what he inadvertently does to Lily’s relationship with her sister, Petunia. As two magical children, Lily and Severus had something in common that Petunia could never understand. Compounded by Albus Dumbledore’s kindly rejection of Petunia’s request to study at Hogwarts, Lily’s friendship with Snape set the scene for the future Mrs Dursley’s endless bitterness towards Lily and her son, Harry.
Susceptible to damage and best grown in a container or basket, the petunia needs shelter from the wind and plenty of light. It is also a flower that can, in the language of flowers, mean ‘resentment and anger’. A rather apt description of a woman who never told her nephew how his mother died until she was in a rage: ‘- and then, if you please, she went and got herself blown up…’
In Harry Potter and the Deathly Hallows Harry sees a memory of his mother. She picks up a flower and magically makes it open and close its petals; Petunia is outraged, but filled with hidden longing.
And several more can be found here:
Including Harry himself:
The joy of Harry Potter’s name was that it seemed like one so delightfully ordinary for someone who achieved so much. But when we dig a little deeper, it seems to be a very fitting name for the Boy Who Lived.
The name Harry is the Middle English form of the name ‘Henry’, a name which was favoured by many an English king. Leadership runs deep in Harry’s name, as well as the motif of war – which Harry is sadly very familiar with. Harry is also related to the Old High German word ‘Heri’ which means ‘army’. As one of the founders of Dumbledore’s Army, this seems apt.
Dumbledore, Hagrid, Draco, Riddle, Hermione and Remus are all in that link.
As Dumbledore points out words are magic but so are names. Enjoy these things rather than trying to break the logic in naming. If you were to truly analyse the names of characters in stories and try to find out how they could possibly have been named in advance you'll learn a lot about the names but you'll also find out that if you try to reason it you'll destroy some of the magic and that's what reading is about: magic.
It's not something that only Rowling does either; I can think of many examples in Tolkien's work and I'm sure I could in many other books as well. The beauty here is its simplicity. What would you call these characters? Etymologically speaking they're named very well. That means the author did well because she used the proper names just like you'd want her to use the proper words for what she's writing. Or should wands be called 'branches'?