Migrated questions that were closed a long time after the migration (and as such weren't marked "rejected") are not automatically deleted by the
RemoveAbandonedClosed scripts even if they satisfy all the criteria. As @animuson explains here:
It turns out that questions which were migrated to the site are not eligible for any automatic deletions outside the 30-day deletion for being rejected.
The check ignored migrated questions because prior to June 4, 2019 it was only possible for a migrated question to also be closed if the migration was rejected, which would lock the question, and locked questions are excluded from
RemoveAbandonedClosed. Since that assumption is no longer true, we may want to reconsider that check, especially given a rejected migration would otherwise be deleted despite the lock.
@animuson also added in a comment that "The RemoveAbandonedQuestions check does not exclude migrated questions."
Can the Roomba scripts be updated so that migrated questions are eligible for automatic deletion by both of these scripts? I don't think there is a good reason to exclude migrated questions from being deleted by some of the scripts. This is essentially a code optimization that is based on an assumption that is no longer true, and as such no longer makes sense.
Here is an example of a closed, migrated question that would be automatically deleted by the
RemoveAbandonedClosed script, but is currently surviving due to this exclusion.
Edit: It just occurred to me, if the Roomba scripts are not going to be updated, then it would be good to at least revise the Roomba help page on every site along the lines in this post — or equivalently, the FAQ post on deletion.