XAML parser deletes valid Lo (Other Letter) characters

Describe the bug

In XAML, refer to a property that has Unicode Lo (Other Letter) characters in it:

<f:InputBox Source="{x:Bind Holdⵙᐁ.Preferences.ShowHidden, Mode=OneWay, FallbackValue={x:Null}}" />

Here the Other Letter characters are ⵙ which is Unicode U+2D59, Tifinagh Letter Yas, and ᐁ which is Unicode U+1401, Canadian Syllabics E. Both are valid characters for a XAML identifier under the specification, since they are both in Unicode category Lo (Other Letter). These letters are also correctly accepted in C# identifiers by Roslyn.

In code-behind, create Holdⵙᐁ and Hold properties:

public HoldablesPageⵙᐁ Holdⵙᐁ => (HoldablesPageⵙᐁ)base.TargetViewModel;
public string Hold => "Hi";

The supporting class HoldablesPageⵙᐁ should be defined with a Preferences property.

Compiling, observe the error stating that Preferences is not a property on string. Since the type HoldablesPageⵙᐁ does have a Preferences property, this demonstrates that the wrong property, Hold, is being bound to instead of the correct property, Holdⵙᐁ.

Why is this important?

This creates a situation where valid C# identifiers run into a logjam when there is a need to refer to them in XAML.

The specification is not implemented correctly.

Yes I actually do want to use these characters in XAML!

Steps to reproduce the bug

See description above.

Actual behavior

XAML picks up the property name omitting the non-Latin characters.

Expected behavior

XAML should follow the spec and recognize all Lo (Other Letter) characters in identifiers.

Screenshots

No response

NuGet package version

VS version 18.7.0, Windows App SDK 2.2.0, TFM .NET 10.0

Windows version

No response

Additional context

No response

Start by reproducing the XAML binding with the Holdⵙᐁ and Hold properties, then trace the XAML identifier parsing and name-resolution path. Compare its handling of Unicode Lo characters with the XAML name grammar and add a regression test; done means the binding resolves Holdⵙᐁ and its Preferences property rather than Hold.