I don't think the way through which you created the OSCustomizationSpec has anything to do with it.
But if you do it through PowerCLI, you have documentation how it was done (the New-OSCustomizationSpec cmdlet and it's parameters).
I would suggest to go that way, and then we can try to figure out why it is not doing what you want it to do.
Is probably a lot easier than trying to logon to a host with a random name :smileygrin: