I'm looking for any manga, manhua, or manhwa... even other languages books that was translated into English that has a female protagonist but was transported back in time or to another world.

Owner of Tainted Sins & Forgotten Scans
Head Manager of Happy Tea Scans

Kumo Desu ga, Nani ka?
Kuma Kuma Kuma Bear
Saving 80,000 Gold Coins in the Different World for My Old Age
Potion-danomi de Ikinobimasu!
Mahoutsukai no Insatsujo
Koushaku Reijou no Tashinami
Isekai de "Kuro no Iyashi Te" tte Yobarete Imasu
While Killing Slimes for 300 Years, I Became the MAX Level Unknowingly
Watashi, Nouryoku wa Heikinchi de tte Itta yo ne!
Otome Game no Hametsu Flag shika nai Akuyaku Reijou ni Tensei shite shimatta...

~4400 manga completed
~1700 ongoing...

Quote from Aremon

Kumo Desu ga, Nani ka?
Kuma Kuma Kuma Bear
Saving 80,000 Gold Coins in the Different World for My Old Age
Potion-danomi de Ikinobimasu!
Mahoutsukai no Insatsujo
Koushaku Reijou no Tashinami
Isekai de "Kuro no Iyashi Te" tte Yobarete Imasu
While Killing Slimes for 300 Years, I Became t ...

Thank you so much 🙂

Owner of Tainted Sins & Forgotten Scans
Head Manager of Happy Tea Scans

Peerless Alchemist
They Say I Was Born a King's Daughter
Jashin Average (Novel) (I've only read until the point that it seems like it would be the end of the series, but apparently isn't)
Otome Game no Burikko Akuyaku Onna wa Mahou Otaku ni Natta (Novel) (I read this for like 50 chapters, I do not know what has happened since. It could be bad now. I don't know. The 50 chapter I've read were good though) (An Otome Game's Burikko Villainess Turned into a Magic Otaku)
Feng ni Tianxia
Fushigi Yuugi (old school isekai, nostalgia manga. Does this even count anymore?)
Houshin Shinai Engi
Fukushuu wo chikatta shironeko wa ryuuou no hiza no jou de damin wo musaboru (A Vengeful White Cat Lounges Around on the Dragon King's Lap)
Honzuki no Gekokujou (Ascendance of a Bookworm)
Seijo no Maryoku wa Bannou desu (The Saint's Magic Ability is Omnipotent)
+a no Tachiichi

Here's the tip I use when I'm searching for isekai with female protagonists. When searching isekai-related tags, if you specify Shoujo or Josei, there's a higher chance of finding one with female protagonists. You'll miss out on untagged or shounen/seinen isekai, but if you are only looking for female protagonists, it's a lot faster

EDIT: Wow some of these names are long. I'm going to add the english titles/abbreviations for convenience

Also Suddenly Became A Princess One Day is very good

Ten ni kou (https://www.mangaupdates.com/series.html?id=105109), translated to italian and spanish
Seijo no Maryoku wa Bannou desu (https://www.mangaupdates.com/series.html?id=146149)

The request just shows how useless and nonsensical the term Isekai is.
The Vision of Escaflowne (stick to the TV anime), Fushigi Yuugi, Inu Yasha, Red River and especially The Twelve Kingdoms (Novel) (the anime adaptation is good) would have fallen under the sub-genre if the term "Transported to Another World" wasn´t the most common descriptor back then. Even Narnia, or in our case Allice in Wonderland, fulfills all criteria to be Isekai, lol.

Ashi-Girl or Namida Ame to Serenade are also Isekai but no one outside of Japan calls female demographic manga by that term it seems. Even 7 Seeds comes somewhat close, it´s complicated. Again, search with the category Transported to Another World and so on instead.

Edit: The wiki article about Isekai is a goddam travesty. The impossible to define "genre" is WAY older than the early 90s. Rumiko´s Fire Tripper -part of Rumic World and adapted to an OVA in 1985- is from the early 80s. Even Mira wrote an Isekai with King of Wolves in 1989, before it was cool. Huh. What a genre pioneer. 🤣

I also read EU/US comics and am a librarian.
Manga-Masters, My ANN-Lists + Imdb

Not checking what was already posted...
... from my current reading list and whatever I read tons of years ago that I can think of. Everything from romance to adventure/action. Mostly mary sue-ish. Not sorted.

Webtoons:

The Emperor's Daughter
Doctor Elise
This is an obvious fraudulent marriage
The Tyrant's Older Sister (warning: a bit more adult romance)
Suddenly Became A Princess One Day
As You Wish, Prince

Manga/manhwa/manhua:

Akuyaku Reijo nano de Last Boss wo Kattemimashita
Dad Is a Hero, Mom Is a Spirit, I'm a Reincarnator
Koushaku Reijou no Tashinami*
Isekai de Café o Kaiten Shimas
Saver
Sengoku Strays
In Another World, I'm Called the Black Healer
This Time I Will Definitely Be Happy! (trigger warning: torture mentioned as part of the main plot)
Operation Liberate Men
Seijo no Maryoku wa Bannou desu
Honzuki no Gekokujou
Suijin no Hanayome (trigger warning: male lead is very cold at first, age gap)
Kanata Kara*

*more quality kind of work

Give time when it's needed

So going on residentgrigo's rant, I thought of some older ones that weren't called isekai back in the day;

Kanata Kara
Please save my earth
Shut Hell
2nding Red River

These are some modern ones, all basically are based on light novels or are webtoons; (All of the female leads basically look the same for a lot of them... but they have varying levels of intelligence )
The Duchess' 50 Tea Recipes
Why Are You Doing This, Duke?
Survive as the Hero's Wife
Suddenly Became A Princess One Day
Priscilla's Marriage Request
I Am a Child of This House
Sincerely: I Became a Duke's Maid
Lady Baby
Koushaku Reijou no Tashinami (this one has the smartest protagonist of the lot)

Does the walker choose the path, or the path the walker?