Note that, because the vertex figure here itself is hyperbolic, the circumradius thus becomes non-imaginary again.

Incidence matrix according to Dynkin symbol

x3o3o3o *b3o3*c   (N,M,K,L → ∞)

. . . .    .    | 10NM ♦    KL |    6KL |    4KL   2KL |    KL   4L
----------------+------+-------+--------+--------------+-----------
x . . .    .    |    2 | 5NMKL ♦     12 |     12     6 |     4    4
----------------+------+-------+--------+--------------+-----------
x3o . .    .    |    3 |     3 | 20NMKL |      2     1 |     1    2
----------------+------+-------+--------+--------------+-----------
x3o3o .    .    ♦    4 |     6 |      4 | 10NMKL     * |     1    1
x3o . . *b3o    ♦    4 |     6 |      4 |      * 5NMKL |     0    2
----------------+------+-------+--------+--------------+-----------
x3o3o3o    .    ♦    5 |    10 |     10 |      5     0 | 2NMKL    *
x3o3o . *b3o3*c ♦   4M |   2MK |    4MK |     MK    MK |     * 10NL