Well, lets start from the top, they're both CVVC lists but you're interested in the reasoning behind
- 2 variants of stop/ending VC
- Split clusters
Clusters were split up probably for the sake of recording and otoing efficiency, even if they would eventually create more work for the UST maker. They could be recorded all together (like kla kle kli kl3 kl@) but that would take up more recording time, otoing time, and file space. The goal of the reclist was to be easy to record so that lots of people could make voicebanks, wasnt it?
As for the two types of ending VC... really, they're not different. The [vc] type is sometimes pronounced a little bit faster than the [vc-]. Considering that we've been told to use consonant velocity on every note... differentiating them wasn't really a good idea, I think.