Once upon a time, there was a witch. Who was not wicked. And despite what you hear from many, she was a witch in a fairy tale. Witches in fairy tales are no more all wicked than all the brothers and sisters (whether full, half, or step), or mothers and stepmothers, or fathers and stepfathers, are.
It's merely the safe way to bet, for all of those characters, because tales do not run on characters get all the help they need from the people around them and thus having no real problems. Like the wicked witch, the not-wicked witch is a plot device, deployed at need in the heroine's (or occasionally, hero's) tale.
There is never a guarantee that you will find her, since there are other characters who can do the same plot device duties, and there is never a guarantee that having found her, you will know for a fact that she is a witch, because there are many mysterious, magical old women who might be witches, or fairies in disguise, or stranger things. (Given that we certainly have troll witches, and ogress witches in fairy tales, being not human is not, at that, reason to think you are not a witch.)
On top of that, they are seldom nice, or indulgent, or lenient. (You want any of those, try talking animals. No promises there, but it's possible.) All witches are capable of doing terrible things if you are in the wrong, and frequently these things may appear disproportionately terrible. Whether they are wicked in that case can be hard to determine, since if they do not also deal with characters who are not in the wrong, it would not be visible.
So, if you are looking for a not-so-wicked witch, do you have to cross thrice ten kingdoms? Perhaps, but not always.
There's one, ambiguous way for the (usually) very young. Mostly for heroes, but occasionally heroines. The character offends her by anything from laughing at her to breaking a pot or jug with her food, and she responds by cursing him only to be able to marry one person, which it will require a fairy tale to pull off. Because the character started it, this might be a witch but not wicked. On the other hand, the response is a curse, and often the character must suffer considerable hardship. And, even though it works out in the end, is this proportionate punishment for laughing at someone?
A clear if rare way can occur for the put-upon daughter of the household. Or stepdaughter, or even the hired girl. It happens when the fire goes out, and they need to bring it in from another cottage to save the bother and nuisance of relighting it. In this case, the witch will be within easy walking distance, even closer than any other cottage. Astute souls may notice this is the way that Vasilisa the Beautiful's stepmother sent her off to Baba Yaga, in hopes that Baba Yaga would eat Vasilisa. This is true, and Vasilisa's danger was real; if the stepmother does that, the witch will be wicked. The trick for this one is that the older girls go first, and they may even come back with the fire. Then you go. Be polite. Be very polite, because she is very strict, and then, when they all go off to the ball without you, the witch may help you go.
More varied are the consequences if you meet a beggar woman along the way, and more common. This is one that the heroes can also face, just as the heroine can find a beggar man, or either one can find animals in need of succor. Be polite. Your duties may range from merely addressing her as Grandmother, or hoping her fishing goes well, to sharing your meal. Then you listen to her advice and accept her gifts, because this encounter tells you little about what will happen to you next. (This meeting seldom is a stand-alone fairy tale.) She is also the most likely to remain, forever, completely ambiguous about who she is, and what she intends. And remember that this can happen before or after your arrogant, lazy, rude sisters or brothers meet her.
Then there's going into service. Heroines can go into service for a Mother Holle or the like. It can work much like meeting a beggar woman on the way, though the requirements are rather more: work diligently through all the chores. Also be pleasant to those about. If an oven asks you to take out its loaves before they burn, or an apple tree to pick its fruit before its boughs break, do it. Share your food with the cat, or the birds, or the dog. This is not a certain route to find a witch who will reward you for a good job well done, though it has happened, and has happened often. You still have to obey her directions when receiving your reward, mind you. Or perhaps she sends you into a room and lets you pick which box you want, and you have to listen to the cats when they tell you to pick the small black box (which why sharing your food is so crucial, because the large red one will burn you to death). But you may have to take your wages by stealth and run, with the aid of the cats, or the oven, or the apple tree. If she gives you impossible tasks, and you need their advice, she is wicked. Or her son's advice. The son of a witch is always the son of a wicked witch, though reliable in himself. (At least you can marry him afterward.)
Meanwhile, heroes can go into service, sometimes for a wicked witch, more often for a man -- an evil wizard -- or an ogre or the like. But just as a heroine may be helped by the son of the witch, the boy may be helped by the Mad Ogre's Beautiful Daughter (or possibly servant or captive or unexplained). She has magical knowledge, at least, and can tell the hero how to complete the impossible tasks (without too much trouble if he has to be told twice), and knows what to take with them when they run away, so she can throw it behind them and stop pursuit. Sometimes she can clearly work magic as well, transforming herself and the hero so that they can hide from the ogre or wizard or witch -- and to unbewitch him at the end, after he's been cursed to forget her, so that they can marry. Which gives one of two reliable not-so-wicked witches.
The other one is for heroines. When heroes violate a prohibition and must go on a quest to regain their wives, they may meet old wizards, or the sun, the moon, and the stars, but when heroines violate a prohibition and must go on a quest to regain their husbands, they may meet the sun, the moon, and the stars, or they may meet old women in the woods. Each one -- she seldom meets fewer than three -- gives her shelter for the night, and a gift the next morning, while directing her on to the next woman, as only the third will know what she needs to do. She will need these gifts to bribe the people who are holding her husband captive. For once, there is no talk of their manners, and their courtesy as guests.
Perhaps these witches figure that having to win to East of the Sun and West of the Moon, or seven years of service followed by having to climb a glassy hill, or wearing out six pairs of iron shoes and three iron walking staves, is enough trouble for the heroine.
I need to check to see if I am missing any f your novels. You do fairy tale novels better than anyone I know.
Isn’t part of it purely linguistic? Same word “witch” used to mean “any female magic user” and “female magic user who got her powers from demons”? Where for a male you would use “wizard” or “warlock” respectively.
Obviously JK Rowling doesn’t mean the same thing the Salem judges meant.