The Bug:
When creating a test, a non-existent string is specified as a raw string. It does not matter whether you have created your own test or use the standard test.
Steps to Reproduce:
1. Enter a world.
2. Enter the following command:
/test create minecraft:always_pass
3. Observe what message is displayed in chat.
Observed Behavior:
The "commands.test.success" raw translation key is displayed.
Expected Behavior:
The translation key “commands.test.create.success” is used.
I have also been encountering this issue. It has been present since 25w04a, when MC-279493 was fixed.