Problem:
Right now localisation keys are not working as expected. This can be seen when attempting to override localisation keys from Docsy. Overriding just doesn't work.

For eg. if I add a key such as [ui_search] in /data/i18n/en/en.toml, it's value is never overriden. It's the value set by Docsy that's shown.

Proposed Solution:
This issue is due to the presence of i18nDir property in hugo.toml. This property forces Hugo to look for translation keys directly in the /data/i18n/en/en.toml and i18n/en/en.toml is completely ignored. This change was made in #43211 which attempted to fix local previewing in Windows as POSIX symlinks were not working at that time. This caused all files in i18n/<language> to not be symlinks, rather contain the relative path to the symlink as text. This is invalid TOML and just removing i18nDir in hugo.toml will once more break Windows local previewing.

But this property is causing overall issues and needs to be removed anyway.

Handling symlinks in Windows
Git can create Windows symlinks when configured properly. See https://github.com/git-for-windows/git/wiki/Symbolic-Links and https://stackoverflow.com/questions/5917249/git-symbolic-links-in-windows. In short, one needs to:

1. Enable "Developer Mode" in Windows 10/11, gives mklink permissions
2. Ensure symlinks are enabled in git with (at least) one of:

• System setting: check the checkbox when installing msysgit

• Global setting: git config --global core.symlinks true

• Local setting: git config core.symlinks true

  And not overridden by a lower level config set to false.

Also note, that if you already have a repo checked out, you will need to set the config locally too and switch branches back and forth to get git to realise the change.

See google/docsy#2187 for an earlier issue that was raised and might contain more details.