I will try to describe my suggestion as swiftly as possible.

Issue:

After archiving a project it should be possible to restore a project, hence the linked issue type schemes, screen schemes and workflows schemes are kept as well. The project is archived 'As is'
This is the right approach in my opinion, however how the archived workflow schemes, workflows, types and so on are still kept in the active section.
As a person who endorses "clean desk" policy this is a pain to the eyes.
Also if workflows and type scheme's change, there probably is good reason to it, so restoring old projects should, in my opinion, always leed to a migration, or at least the open question whether the old schemes should be restored or migrated to the newer versions of those flows.
Should there be versioning of workflows? well it is proper management to version SOPs but let's not push this too fa..

Suggestion:

1) keep archived workflows, issue types, schemes, not in the active section but move them to the inactive or even a new "archived" section

2) when restoring an archived project ask for the project to be migrated to the actual active schemes or optionally to restore the old schemes.