You could save yourself a lot of grief by binning the existing W10 installation. Do searches and locate a vendor who can supply Windows 10. This works via a provided link to the Microsoft website for the OS download and the vendor will provide a genuine activation key via email. Microsoft prices are horrendous so look around avoiding the very cheapest offers. It's a long while now since I did this but it worked very well. Avoid any "cracks" or keygen solutions. It's not worth the security risks.
FWIW, I went through something similar to this a couple of years ago. Although certainly not the Korean to English part. I had purchased a copy of Windows 10 on Ebay, only to discover that it was counterfeit when I tried to activate it. M$ told me straight up, "those letters shouldn't even be in the product key".
So, I tried to download the software that allows you to download a Win 10 ISO. Once upon a time, you could do this with Win 7. However, when I tried to run the ISO creator, it told me, "you need to have "Windows XP Service pack 3 (!!!), to run this software. That's about as cutsie-pie a way possible to d*ck you out of being to use Windows 7 to create the W 10 ISO. What will M$ think of next?
So, in spite of it being fake, my copy of W 10 did allow me to download and run the creator and install a W 10 ISO onto a flash drive. (yay?)
Then came the fun part. I bought a Win 10 key from somewhere near and dear to us. Well, the key didn't. work. Emails were exchanged, and the seller tried to tell me what the minimum requirements to run Win 10 several times, in fact. I tried to explain that the machine, despite being rather mainstream, had an i3-12100, 32 GB of RAM, and a 500 GB NVme for C:/, so it would probably "squeak by".
At the 4 hour juncture, I explained to him that the key was either used up bogus, and they could either give me one that worked or my money back. That seems to have done the trick.