Hi snp and J-NET members.
I informed my Juniper SE about issue (PFE image being RE image in reality) and asked him where to report issue. He asked internally. Let's see if there will be some answer.
The vQFX10K 18.1R1 is not published on Vagrant cloud yet (17.4R1 is latest there - version 0.3).
Link: https://app.vagrantup.com/juniper