Attached working proof of concept with LabVIEW CLI, To make it work:
 
	
		Disable Error message on logger instance (FGV in C:\Program Files (x86)\National Instruments\Shared\LabVIEW CLI\Operations\Utilities\Logger)
	
	
		Enable multiple instances of LabVIEW
	
	
		Spawn few labview processes that will run Builder.vi and pass instance parameter eg \..\..\Labview.exe \..\..\Builder.vi -- 1
	
	
		Copy ExecuteBuildSpecAsync_class folder to C:\Program Files (x86)\National Instruments\Shared\LabVIEW CLI\Operations
	
	
		Start it the same way from labview CLI but use ExecuteBuildSpecAsync insstead of ExecuteBuildSpec, should compile on free running builder or throw exception
	
	 
 
builder.zip