Japanese and Korean texts don't work properly on Skia backend, altought they work fine on Direct2D backend.
Examples:
Japanese Example: 日本のテキストの例
Korean Example: 일본 텍스트 예제
Repro steps:
Add this textboxes to control catalog core project:
<TextBlock Text="Japanese Example: 日本のテキストの例" />
<TextBlock Text="Korean Example: 일본 텍스트 예제" />
result:

Same action on control catalog desktop is working fine:

Thanks for reporting this. I am currently working on a new text layout for the skia backend that should handle these characters just fine.
@Gillibald , I saw that you had PR #3438 Would this fix it as well. I'm working on an internationalized app.
Yes. You will be able to use non Latin text in TextBlock.