Intrinsic angle defect is not ambient curvature

Let

At the transverse central event, dot products of the two boundary rays within an $E$-face give cosine $-1121/1921$; within an $N$-face they give $671/1921$. The other two faces are reflections. Hence

To check the sign, $A>\pi /2$, and

Thus $B>\pi -A$.

At an incoming triple junction, the two equal face angles have sum $\pi +A$, and the remaining angle is $B$. For example the equal-angle cosine is $-39/\sqrt{1921}$, and the double-angle identity gives that sum. The defect is $\pi -A-B={\kappa }_0/2$. The outgoing calculation interchanges the two pairs and has the same result.

The marking therefore redistributes a transverse intrinsic angle defect while the ambient metric remains fixed and locally flat. This is not a bounce or the creation of spacetime curvature.