[Pega 25.1.3] Issue with Localizing Dynamic Messages in Constellation

Hello Community,

I am facing an issue with localizing dynamic messages using the Constellation UI architecture in Pega 25.1.3. My goal is to use dynamic messages based on Rule-Message instances that contain placeholders (e.g., “Message {1}”).

I followed the official documentation closely to override the ‘pyMessages’ localization rule in @baseclass:

Despite following all the steps , the translations are not being applied at runtime. The text remains entirely in the source language.

Crucially, this issue is not limited to my custom rules. Even (OOTB) dynamic messages—such as “The resource that is being accessed is locked by {1}.”—are not translated.

Has anyone successfully implemented this functionality in Pega 25 / Constellation? Could you share a working example or shed light on the exact configuration details required to make this work or are there any known limitations regarding functionality in this specific version?

Any insights or working examples would be greatly appreciated.
Thanks in advance
Tomasz Sukiennik