>>537844000 (nta)
To add on to this, it feels like Joe doesn't know how to write characters that feel believable. Now, this is something hard to believe, as we didn't see any writing come from him aside from a few snippets here and there, but those all lack the full context.
I'm not going to psycho-analyze him to determine if he's a good writer or not, as not only am I not qualified for that, but also, there's a lack of information.

Like, why did the Amy vessel talk about Undertale? Why specifically that game and not something else? Was it because the Amy vessel likes that game, or is it because Raven likes the game? Now that I think about it, we barely know anything about the characters outside of Sonic.

Was a timeline in reference to the real world ever given? Who knows, we know jack shit about the characters as there's no comic or game to refer to as a guide.