As to the error "Unable to edit this saved form because the corresponding blank form is not present or was deleted", it's an old problem.
Your finding is true for ODK Collect 1.9.x too. What's more, the same thing occurs if you reload a new version of the same form without any or any significant changes to the server (your own install or ONA, KOBO etc.) from where you re-pull the blank form to your Android device (from where you deleted it) because the replaced form will get a new form ID. >> for a possible solution see my post here on how to replace the form ID string in the unsent Finalized or Draft Submissions:
Of course, for a very large number of unsent submissions it is rather troublesome.