This is one of our top priority tasks, but due to (techincal) complications between Geocaching.com and Project-GC we have had to prioritize other things related to the challenge checkers.
For example there has been a few bugs in the API that has been resolved, this has costed us a lot of time to investigate and figure out why finds has been missing for some users and so forth. We are also working on getting the lab caches included.
We had a time schedule that was reasonable, but when things didn't work out it started to collide with other things in the planning which has made the last months very hard to actually plan out.
Right now we are working on major database designs to get the Lab caches working correctly at Project-GC. This will affect a lot of code on the site which is unfortunate. After that I hope that we can get back to the checker framework again.
I am sorry for not giving a more absolute answer.