Some of them are a bit nitpicky. Especially the one on Ascian/Ancient lore. You can get lore from side quests within the game, which are also optional content—but everything necessary to understand the main scenario is always brought up in some way during the course of the main storyline. Even if the tidbits can also be found in the optional content. Your understanding of the Ancients and their society will not lack from not speaking to Emet during the 5.0 MSQ, but he does give “advance knowledge” on certain things you’ll hear about down the road.
It’s kind of the same for the CT series argument. Yoshida stressed repeatedly to revisit the story prior to ShB launch—and in 5.3, made completion of CT mandatory to even get to HW. So it’s not like he didn’t try to hint at the importance. The team also did various adjustments to make unlocking the raids and progressing through their storyline much faster compared to in the past (such as removing the FATE requirements).
I can agree that Urianger’s way of speaking gets irksome after a time. The only reason I can give for why they have him speak as such in English is because, in Japanese, he uses highly formal speech patterns. As English doesn’t have a formal speech equivalent, I’m guessing they thought his dialect was the best they could do.
Urianger isn’t using Old or Middle English. Old English would be near unintelligible to us, and Middle English not far behind.
A fun sample: The Lord’s Prayer in Middle English.
Oure fadir that art in heuenes, halewid be thi name; thi kyngdoom come to; be thi wille don, in erthe as in heuene. Yyue to vs this dai oure breed ouer othir substaunce, and foryyue to vs oure dettis, as we foryyuen to oure dettouris; and lede vs not in to temptacioun, but delyuere vs fro yuel. Amen.