The equality conjecture for the volume of the even-dimensional Eisenstein orbifold

Let $n \in 2\mathbb{Z}_{\geq 1}$. Write $\Gamma^n_{\mathrm{eis}} \setminus \mathbb{R} H^n$ for the non-arithmetic hyperbolic orbifold $M({\mathscr{L}}_{\mathrm{eis}}^n,\alpha_0)$, and let $\operatorname{PO}(\Psi_i^n,\mathbb{Z}) \setminus \mathbb{R} H^n$ be the associated arithmetic hyperbolic orbifolds. The equality conjecture. The bound in equation is an equality; equivalently,

$$\operatorname{Vol}\left(\Gamma^n_{\mathrm{eis}} \setminus \mathbb{R} H^n\right)=\sum_{i=0}^n\operatorname{Vol}\left(\operatorname{PO}(\Psi_i^n,\mathbb{Z}) \setminus \mathbb{R} H^n\right).$$

This predicts that, in every even dimension, the volume of the non-arithmetic hyperbolic orbifold is exactly the sum of the volumes of the associated arithmetic orbifolds. The source gives no resolution of the expected equality.