The flag-accuracy conjecture for extended Catalan arrangements

For a root system of Dynkin type, let $\operatorname{Cat}^m$ denote the corresponding extended Catalan arrangement. An arrangement is flag-accurate when it admits a flag satisfying the required accuracy condition. Extended-Catalan flag-accuracy conjecture. Extended Catalan arrangements are flag-accurate. The claim is known for extended Catalan arrangements of Dynkin types $A$, $B$, and $C$; the paper highlights type $D$ as unresolved, so the general assertion remains open.