I think the reason that they aren't in the CH tabs is because they are side-characters. I don't recall any by the name of Amos, probably because I forgot or they might be in Ander's route, which is the only one I haven't read.
Braum and Gordon are the member of Highwell Uni.'s basketball team, you can see them talking to us in the gymnasium in Gil's (don't call him Gilbert) route.
Alex, if I recall correctly, he's Mark's brother. You can see Mark knocking on a certain door at his home when he was heading off to school or going out in Mark's episodes, albeit his knock was never answered because if I'm not mistaken, Alex is already dead. Mark just knock the door for the sake of remembrance.
Edgar is Walter's (our MC) father. He's friend with Mark's dad: Mr. Thorton, who is the owner (or a board director) of Lars' previous workplace. Not much could be said beyond this point since some of them were in the patreon build.
Albeit, I find the lack of story progression at the moment to be quite irritating, but perhaps Andy had something in mind and that he's still building up until it all reveals.