Your query was pretty helpful. I've been cherry-picking some examples that show up as being deleted twice. Let's take a look at the timeline of the highest voted post there:
- It was deleted by the roomba
- It was undeleted by a vote from OP and another user.
- There was a comment by the OP: "Not sure about the downvote - there seems to be a problem with hashed/unhashed entries in known_hosts. I'm going to dig into it a little further and answer the question."
- It was deleted by roomba again
- It was undeleted again by OP and another user.
- It was self-answered
After that, it was never deleted again. This is the timeline of the second-highest voted post that shows up twice. Again, it was deleted, undeleted, nothing else happened, it was deleted again, then undeleted, then it got a bounty and finally an answer blocking further deletion. And this is the only other post I found with a positive score that was deleted by the roomba twice: First for being a closed question, then for being 30 days old.
Another one, that's still scoring 0 and is closed, was also deleted and undeleted by a mod twice. But, looking at the vote summaries, it had an upvoted answer before it was deleted and undeleted. It seems more likely the Roomba was already wrong the first time it was deleted! Another one that was deleted twice: Asked and answered by the same person, but with only 60 views after 5 years.
All in all, there are 7 questions on that query that were deleted by the roomba twice. And only 3 now have a positive score. On a site the size of SO... that's negligible.
With the exception of the three positively scored questions, I'm not sure how valuable these questions actually are to people. And I'm not sure how much value there was in undeleting them in the form they were in. First step to me would be making sure that if a question that was deleted by the Roomba is undeleted, there's a good reason for doing so. This would include having a discussion somewhere on meta about reopening it, or having a self-answer ready for posting the minute it is undeleted. In short: when considering to undelete something deleted by the roomba, do something to make it ineligible for a second roomba deletion.
If it is really that impossible to make these posts ineligible for Roomba deletion forever in the short time they are undeleted, give them a longer time before being deleted again. But don't make them ineligible forever. If they were deleted as e.g.
RemoveAbandonedQuestions, make undeleting count as 'resetting the timer'. That way such a question will have a whole year again to attract upvotes and an answer. If it was deleted as
RemoveDeadQuestions, give it another 30 days. That should be more than enough time.