So, I decided to give it a try. I've finished processing available source localization files with machine translation tools and started the manual review process. It will take a long time, so let me know if you want to participate - any help would be greatly appreciated, and it shouldn't be complicated, as I'm using Weblate to manage this process.
Nevertheless, you can find the initial release here: github.com/Raschert0/underrail-translation-uk/releases
Just take note that some strings might be really messed up. Feel free to report any issues here.