Hurrah, the "batch file on same drive as EECH" constraint is no more!
The command prompt just needed to be switched to the EECH drive right from the start. Otherwise, Windows tries to open H:\Plane Games\...\cohokum.exe instead of K:\...\cohokum.exe.
The code is updated in the second post.

Viper1970, I have to be honest : I can't get involved in another project for the moment. When things settle down a bit, I'll be happy to contribute.