Very nice Implementation, I shortly tested it in my Application and it was working well.

I have some suggestions, since we don't have many strings, why not add strings for all Languages into the Library by doing community translations, there are many free services that generate resx files from user inputs, users can review changes made by others and submit new translations. Or we could start with sample machine translations.
Here is an Example of how it could look with an existing project
https://crowdin.com/project/Evolution_X/de

Very nice Implementation, I shortly tested it in my Application and it was working well.

I have some suggestions, since we don't have many strings, why not add strings for all Languages into the Library by doing community translations, there are many free services that generate resx files from user inputs, users can review changes made by others and submit new translations. Or we could start with sample machine translations. Here is an Example of how it could look with an existing project https://crowdin.com/project/Evolution_X/de

@Bush-cat Thanks for your suggestion! I completely agree that having translations for all languages would be great. For now instead of using Crowdin, I’d prefer to accept translation contributions directly on GitHub. Feel free to open a PR with your own language translations—we’d really appreciate it!

very clean design !!

some minor flaws:

TableViewDateColumn: Line 67: this always stays as 'pick a date'. since the DP has a default. Consider dropping the DependencyProp.

TableViewColumnHeader.xaml: Line 158: remove PlaceholderText in Autosuggestbox, since set in code.

TableViewTimeColumn: missing Placeholder setter for TimePickerControl

TableViewTimePicker: consider dropping PlaceHolder DP

TableViewColumnHeader: consider dropping Descriptions for 'SelectAll', 'DeselectAll', 'Copy', and 'CopyWithHeaders', since they are sort of redundant, and well described in the command.

TableViewLocalizedStrings.GetValue(string name) I don't understand why you need TryGetValue(..) and then GetValue(..) if first returns null ??

Thank you, @VisualAlf! I've made the changes and am merging the PR now. Regarding the descriptions, they are just tooltips for the menu items. As for your last point about TryGetValue, the reason for that is if the resource isn't found, the next line ensures it falls back to the default language resource.