Info on the first / second pages explain how they should be named to ensure they are grouped.
And ensure there are enough groups to chop blocktransform objects down, using multiple KSTREE_GROUP_X_ groups.
Like KSTREE_GROUP_TYPEA_OBJECT.000
Like KSTREE_GROUP_TYPEA_OBJECT.001
Like KSTREE_GROUP_TYPEA_OBJECT.002
Like KSTREE_GROUP_TYPEB_OBJECT.000
Like KSTREE_GROUP_TYPEB_OBJECT.001
Like KSTREE_GROUP_TYPEB_OBJECT.002
Also, theres rarely a need to have that many Y tree meshes, its recommended you created a long wall type object with repeating texture to cover areas further out. Also explained in the first few pages.