I have found a bug in 12.8 and 12.7 Launchbox.
If you use a custom Dosbox Version (use own Dosbox Version) in the Launchbox Meta Configuration for the Game,
this custom Dosbox is used only for start the Game/App Path but not for the Configuration Path that is selected for Install.exe or Setup.exe or something like that.
That is bad because Games wont be configured correctly for the own Dosbox Version.