The trouble regarding the epilogues is that they are explicitly stated to be dubious canon, iirc this is where the term originates. I would propose that this and Hiveswap are equally canon and therefore both dubious, while one is post canon and one is pre canon. friendsI’m and pesterquest are an alternate timeline, aradia and dirk’s chapters show this. in another work these would be completely untrue, but homestuck supports other timelines and thus I believe it should also be considered dubiou. HSBC, on the other hand, is a further level removed from the original. so, homestuck is at the top, then the epilogues, friendsim, and Hiveswap branch off of it in fully separate and equal but not mutually exclusive realms of dubious canon, and the BC exists at the bottom, in a state similar to how you describe post canon.