Translation Keys Not Replaced in Static Output

[vitalpepper]

When using Statamic v5 with the official statamic/ssg addon to generate a multilingual static site, translation keys stored in resources/lang/{locale}.json are not replaced with their translated values in the generated static HTML. Instead, the raw keys (e.g., "welcome_message") are rendered literally.

📦 Reproduction Repository

You can find a minimal reproducible project here:
🔗 https://github.com/vitalpepper/ssg-trans

the repo is also compressed in a ZIP file inside the repo with file name ssg.zip

✅ Steps to Reproduce
Run SSG in the Repo

php please ssg:generate

🟢 Expected Result
The translation keys are correctly replaced during static build:

<!-- For EN -->
<h1>Welcome</h1>

<!-- For DE -->
<h1>Willkommen</h1>

🔴 Actual Result
The raw translation keys appear in the HTML:
<h1>welcome_message</h1>

Environment
Application Name: Statamic
Laravel Version: 12.2.0
PHP Version: 8.4.4
Composer Version: 2.8.6
Environment: local
Locale: default

Statamic
Addons: 1
Sites: 2 (Schweiz, USA)
Version: 5.50.0 PRO

Statamic Addons
statamic/ssg: 3.1.1