Alex

The easiest answer for the Kibito Kai issue is simple: Toriyama forgot again. He decided he liked the original design for Supreme Kai more, he wanted to do a story focused on him, and forgot he still had him in the fused form in the first few arcs of Super (as his part was very minimal at the time). Maybe they'll remaster Super in the future with the retcons in place, and if anyone asks, Kibito was hanging out with Launch and Android 8 for a bit. As for Goku not going SS4, in canon it could simply be that it doesn't work outside the demon realm (which may be revisited in the final arc Toyotaro is working on). In real life, Toriyama forgot about the "final form" detail in the fight with Beerus (or didn't write that bit of dialogue to begin with). Additionally, Vegeta not going SS3 against Beerus can also be explained by his attack being a reflex action, and at the time going SS3 would've still taken some concentration. At the end of the day, Toriyama was never the best at keeping continuity straight on his own. Combine that with supervising different teams working on movies, anime and manga all taking place at different points in the timeline (and most importantly the state of his health at the time), it's understandable that some details would've slipped through.