Rita screams are more than "not getting what they want". For example, their scream is shorter and crisper in ep9(00:24) and ep25(00:53) when they want to be a part of the team. Most times it's about releasing stress before doing extra work that has to be done, in Rita's words, "If one doesn't releases stress occasionally, one will explode" (ep24).
I too personally found it not only funny but also personal since this could be his way of releasing his stress. Plus, whenever they scream, it was never to the point of infuriating annoying like “Yossha Lucky” or Takaharu’s “Moekita”.
screm But also If you think about it Rita having screaming as their main stress release method makes sense. Y'know, since *they had to rule the kingdom SINCE THEY WERE 10.*
Do NOT listen to their screams at MAX VOLUME. I TRIED, IT'S GENUINELY SCARY AND I UNDERSTAND HOW EVERYONE ELSE FEELS WHEN THEY SCREAM (apparently only Jeramie doesn't mind that) And is it me or during the timeskip they don't do this as often? The last time was probably when they're in Yanma's body 🤭