[sciurius]

To test it, I created three new songs and edit their contents to have resp.
{key: Cminor}
{key: Cm}
{key: C m}

The songs have one song line: [A]Hello.

When I open the songs and long-click on the screen, then use the transpose dialog (the quarter note with the arrows), only the song with Cm is understood to have key Cm. All other get key A (inferred from the first chord of the song).