That is expected because the message is generated before the redirect and thus before the setting is actually applied to the system.
Going to close this as expected behavior.

No... I think, message should be generated later.
Technically you can not print the message until you did not get the response.

The message is generated before the redirect, after the configuration was successfully saved.
After that the browser gets redirected and reloads the page.

Now the changed configuration is in effect, but the message is already generated. It will just be read from the session and displayed. Thus there is no way to detect if it was translated or hardcoded.

It's the way Joomla messages work.

Okay! I accepted whatever you said, I am not technically strong. I raised this issue as an end user.
Thank you.
Have an awesome day.