Expanding our support for authors is a big initiative for us this year and the importance of CTR for authors isn't lost on us.

We've actually just started talking about getting the rules to work on a CTR threshold as an option rather than using conversions. We have added this to our product roadmap but development timelines have not been scoped out yet. In the meantime, we suggest living in the search term explorer. This aggregates your search terms across your account and gives you the aggregated metrics. We don't have an export for this yet, but we suggest just copying and pasting this into excel to manipulate it. Specifically, sort by CTR.  Even with this manual process, it's going to save you tons of time scouring through search term reports across the whole account.

Here's the best way to grab the data from the explorer:
If you do that, it should copy/paste cleanly into excel and you can manipulate as needed.

Beyond that, the rules will still add a ton of value as conversion is still a great metric for authors (just not the only one) and then we'll have the CTR triggers for the rules eventually.

From a bid optimization standpoint, we use an ACoS target on the campaign level. We suggest setting a higher ACoS target (70-100% range or even higher possibly) as authors are getting revenue from reads and not just conversions which is different than the product world in Amazon. Hopefully, Amazon will surface some more KDP metrics on the API soon and we'll be able to take that stuff into account too!!!