Its not the timed ones that are really a problem on ones like chloris. Its needing 4 different KIs that are not guaranteed drops and needing 2-3 different pop items to pop most of the ki nm. And you have to go through that process 25-50 times, and are only able to hold 1 set of the KIs. There just is not a good way for doing this solo. Also in the case of Chloris, there is only one timed nm for the pop set which is fairly low spawn time to begin with. There just is not a way to efficiently farm ones like to this without a group.
I have done both, killed the NMs and amber cleaved, even mixed the two. Each takes a similar amount of time solo for one that does not have all the event items needed to reliably proc.
The one thing that would help the most is being able to hold more than one ki popset especially on the ones needing multiple KIs. As I know I have not felt held up by timed NM spawns while doing this.