Currently ConEmu loads only first icon from binaries that contains multiple icons. I'll try fix this, also may be try to implement loading icons from shell associations (found TODO comment for that in you source)
Well, for example.
ConEmu autodetects "Dev 14 command prompt" as task. Best icon for this task is icon 33 from %CommonProgramFiles(x86)%\microsoft shared\MSEnv\VSFileHandler.dll but ConEmu can load only icon 0 from exe and dll files