There is always room for improvement 
I had some issues with “leftovers” but it was caused by faulty install scripts and sorted by adding the dismount in the catch of deploy-application.ps1.
I think but have not verified that the mounted WIM’s are not remounted at boot which makes a reboot a “fix all” problem when it comes to this issue.
The only problem I have faced is that Zero Config MSI-installs doesn’t work as expected. The WIM is mounted after running the logic which decides if it is a Zero config MSI or not. Because of this the MSI is never installed.
Quick solution is to run Execute-MSI even though it should be run as a Zero Config MSI.
Please let me know if you have any problems.