Gathering data from Wikipedia in many cases needs valid title. This title can be changed in history, and all tools that depend on title fail to give data for changed title.
Is there a credible programmatic way to find title change in page revisions?
You can record the page ID and request the page by that instead of the title (in the API, use the pageids parameter). It's not entirely impossible for page IDs to change (when pages get deleted and recreated in tricky ways) but normally it does not happen.
If you specifically need the past titles of a given page, I don't think there is a nice way to do that. For a non-nice one, you can try the list=logevents API query to get the page rename logs.