If I use strings instead of localisation strings in the "Author" field of the SCR_MissionHeader config file then this results in in a suffix #AR-AuthorLoadingScreen. If, for example, my name is "y0014984" and I put that in the author field then I can read "#AR-AuthorLoadingScreeny0014984" in the mission loading screen.

The root cause seems to be line 97 in SCR_LoadingScreenComponent.c

m_Widgets.m_wAuthor.SetTextFormat(AUTHOR_FORMAT + header.m_sAuthor);

I think it should be like this:

m_Widgets.m_wAuthor.SetTextFormat(header.m_sAuthor);

If I use localisation strings instead of regular strings this issue does not appear.