In the current UI I can easily see to which environments a version went.
I cannot quite as easily get an overview for an environment itself and get a history of which versions were deployed to it.
unless i am missing something obvious 
Maybe you can change the link which exists in the projects overview on the environment names to not link to the general environments overview, instead link to a special view of the releases, which are deployed to the selected environment.
Something like: Project name => Releases => Deploy to DEV (=> 1.2.0)
This would help much to see a history of the deployed versions to this environment.