The coefficient $p_{c'}^{c}$ in a formula in Lusztig's canonical basis paper

Question

In Lusztig's paper Canonical bases arising from quantized enveloping algebras, the formula (a) in Section 9.4 on page 483, there is a formula \begin{align} \tilde{\gamma}_c' = \sum_{c' \le c} p_{c'}^c \gamma_{c'}'. \end{align} It is said that the coefficient $p_{c'}^c$ is the (formal) alternating sum of the eigenvalues of the Frobenius map on the stalks of the cohomology sheaves of $\mathcal{P}_c$ at any $F_q$ rational point of $\mathcal{O}_{c'}$. In the paper Nilpotent orbits of linear and cyclic quivers and Kazhdan-Lusztig polynomials of type A, on pages (3), (4), it is said that $p_{c'}^c$ is related Kazhdan-Lusztig polynomials. Is there some results in type $D, E$ in the literature about the coefficient $p_{c'}^c$? Are they also relate to Kazhdan-Lusztig polynomials? Thank you very much.