Is there a way to apply that limit to titles instead of chapters?
No, because the feed tries to retrieve, sort and limit the page result by chapters. Collating the chapters that are returned for a given page by title is just a frontend feature to make the search result read easier. While it is technically possible to do things by title, it's going to be a very expensive operation (and that while the feed API call is already the most expensive call MangaDex has), so you can't expect that to happen.
A worse solution would be for uploaders to flag chapters as "old" or "reuploaded" so this does'nt happen.
There's still a "planned" suggestion that's been open for years by now to
allow for silent uploading, but that would only affect the recent updates section on the homepage. Outside of that, there has been talk about being allowed to set the publishing date in the past, but I think that's even further away from development...
Either way, the massive upload spam is long over by now. If you're concerned about not being able to find the chapters you might have missed due to the flood of official publisher chapters or you just don't want this to be an issue in the future, I suggest trying to
block the account that the bot uses to remove the official publisher chapters throughout the site.
If you're interested in checking out the official publisher chapters, then you can always remove the block whenever you don't need it anymore and reapply it whenever needed.