There is an issue with the translation/localization feature for Custom Sidebar Sections/Links.
If a custom sidebar section or link is created while the site’s default locale setting is set to Language A (e.g., English), but the site’s default locale is later changed to Language B (e.g., Hungarian), the existing custom sidebar records do not adapt to the new default locale.
As a result, the UI misinterprets the base/default input field, causing language options in the translation dropdown to be completely swapped and scrambled.
Steps to Reproduce
Set default locale Site Setting to English.
Create a new custom sidebar section/link, but enter the text in Hungarian (because the user locale was Hungarian for me) (e.g., set base label as "Főoldal" and path as "/"). I didn’t localized it because there wasn’t a feature to do this yet.
Change the site’s default locale Site Setting to Hungarian (hu).
Edit the custom sidebar section created in Step 2 and try to translate it:
Observed behavior: The system now assumes the base input field ("Főoldal") is the Hungarian base value because the site default is Hungarian.
In the translation dropdown, Hungarian is no longer available (since it’s now treated as the base language), but English appears as a selectable translation option.
Selecting English in the dropdown and entering the English translation ("Homepage") causes the localized values to be inverted or mismapped.
