Indecomposability conjecture for traces of universal $PGL_3$-monodromy

Let $S$ be the surface under consideration, let ${\cal X}_{PGL_3,S}$ be its moduli space of framed $PGL_3$-local systems, and let $n$ be a positive integer. A good positive Laurent polynomial on ${\cal X}_{PGL_3,S}$ is a positive integral Laurent polynomial in every canonical coordinate system, and it is indecomposable if it cannot be written as a sum of two non-zero good positive Laurent polynomials. Indecomposability conjecture. The trace of the $n$-th power of the monodromy of the universal $PGL_3$-local system on $S$ around any loop on $S$ is indecomposable. This claim concerns the positive Laurent-function structure on the moduli space and asserts that these trace functions cannot be decomposed into nonzero positive pieces; the supplied text gives no resolution status or further evidence.