I've reverse engineered Sai 2 a bit but not enough to map out the newer sai2 file format yet.. Since sai2 is actively being developed too I'll very likely have to "wait" for Sai 2 development to "settle down" for a little while before I go diving into the file format since one update SYSTEMAX makes can potentially break any confident research and tools I made at a specific version...
I'll look into it more in the future since the file format is probably not going to be changing drastically any time soon but we'll see!