Wrong font for unpackaged WinUI 3 apps on Japanese systems

[enitimeago]

Describe the bug

Running an unpackaged WinUI 3 app on Windows 10 and Windows 11 set to Japanese does not use Segoe UI for rendering English text.

When running as packaged, English text uses Segoe UI as expected.

Steps to reproduce the bug

1. Set system default language to Japanese
2. Clone and open the Sample.WinUI project in https://github.com/enitama/XamlPlus.WinUI
3. Run "Sample.WinUI (Packaged)", notice English text renders using Segoe UI
4. Run "Sample.WinUI (Unpackaged)", notice English text renders using a different font (possibly Meiryo UI?)

Expected behavior

App when unpackaged should still use Segoe UI for English text.

Screenshots

Packaged:

Unpackaged:

NuGet package version

WinUI 3 - Windows App SDK 1.2.5: 1.2.230313.1

Windows version

Windows 10 (20H2): Build 19042
Windows 11 (22H2): Build 22621.1413

Additional context

No response

[enitimeago]

I've reproduced this issue on Windows 11 22H2 as well, updated the details above.

[sotanakamura]

Packaged app uses Segoe UI, packaged app with "Language=jp" uses Yugothic UI, unpackaged app uses Meiryo UI, and self contained unpackaged app uses YuGothic UI.