I see that the API proposed here is still being worked on (it was updated 11 hours ago):
https://github.com/pi-hole/FTL/pull/659
Maybe @ScrewGravity and @DL6ER can coordinate? I was looking at the code of this new FTL API some days ago and I think it great what they are working on. Especially that they are doing server-side pagination. It is worth to check out the individual commits, @DL6ER is always describing what he adds and you can learn a lot from him. Everything is separated into small pieces with clear titles so there are no huge +/- 1000 lines as you can find in many other open source projects where everything is squashed into big commits, defeating the idea of commits IMHO somewhat.
Take, for instance f241287 Add /admin/api/stats/database/overTime/history - this allows users to select a different time interval on the dash board than only "last 24 hours".
When you can work on this together, I think this can be the way to go. Fitting new things to the old (and conceptually at least questionable in many aspects!) API seems wrong when there is already something a new RESTy in the works.
What do you think @ScrewGravity?