The data matrix for the cladistic analysis of Pachycephalosauria in your paper should be revised to reflect the following:
(1) Evans et al. (2021) find "Troodon" bexelli to be a valid pachycephalosaurid taxon and erect the new genus Sinocephale for it, and they demonstrate that Sinocephale was uncovered in the Ulansuhai Formation based on stratigraphic fieldwork in the type locality of this taxon by You Hailu, effectively making Sinocephale the oldest pachycephalosaur from East Asia.
(2) The taxon Gravitholus albertae that you include in the pahycephalosaur cladogram is synonymized with Stegoceras validum by Dyer et al. (2023) based on CT scanning of the holotype of G. albertae and morphological comparison with S. validum specimens demonstrating that this specimen is an extremely mature Stegoceras validum judging from not just the extreme cranial fusion but also regions of the dome of TMP 1972.027.0001 with cranial sutures that are less fused than those of the interfrontal, frontoparietal, and right posterior supraorbital-postorbital region. Dyer et al. also consider Hanssuesia to be a junior synonym of Stegoceras validum (the recovery of Hanssuesia as basal to Amtocephale and derived pachycephalosaurids in your cladogram is refuted by the phylogenetic analysis by Evans et al. , who recover Hanssuesia in the clade you term Stegoceratinae, which is consistent with Amtocephale being much younger than Hanssuesia or Stegoceras).
To be honest with you, recognition of the Gravitholus holotype as an extremely old specimen of Stegoceras validum reminds me of when AMNH 5450 was first named Stegoceras browni and later renamed Ornatotholus (it was even seen in some books as a Homalocephale-like pachycephalosaur), before being eventually recognized as a juvenile specimen of Stegoceras validum by publications in the late 1990s and onwards.
Dyer, A. D., Powers, M. J., and Currie, P. J., 2023. Problematic putative pachycephalosaurids: synchrotron μCT imaging shines new light on the anatomy and taxonomic validity of Gravitholus albertae from the Belly River Group (Campanian) of Alberta, Canada. Vertebrate Anatomy Morphology Palaeontology 10 (1): 65–110. doi:10.18435/vamp29388.
Evans, D., Brown, C.M., You, H., and Campione, N.E., 2021. Description and revised diagnosis of Asia's first recorded pachycephalosaurid, Sinocephale bexelli gen. nov., from the Upper Cretaceous of Inner Mongolia, China. Canadian Journal of Earth Sciences 58 (10): 981–992. doi:10.1139/cjes-2020-0190.