They aren't 'jointing things' they are for tensioning the blown fibre tubing I believe.
In the document for the fibre locking mechanism, it shows the 36-fibre "ultra lightweight aerial fibre" (which is also included in your earlier architecture diagram).
I can understand the need for locking this kind of distribution fibre, but I would have thought it wouldn't be possible for BFT. Surely putting multiple figure-8 in BFT is going to make it impossible to blow the fibre in later?