Headscratchers / In Another World with My Smartphone

Per wiki policy, Spoilers Off applies here and all spoilers are unmarked. You Have Been Warned.

• When we’re first introduced to Elze and Linze, they are caught in a disagreement with a pair of clients who hired them to get a crystal deer antler. After the clients refuse to pay the proper amount and Touya helps them, the two of them (along with Touya) join the adventurer’s guild, saying that they probably shouldn’t have been doing missions outside of a proper place like the guild. But, there doesn’t seem to be any real effort involved with joining the guild, besides some paperwork and maybe an entry fee. So, if that’s the case, why were they doing outside work in the first place?
  • Adventurers have ranks and can only take on jobs within those ranks, most likely Elze wanted to get as much money as early as possible without ranking up from low-paying jobs, also factor that the twins bought new gear after Touya paid them(greaves for Elze and a wand for Linze) and rented in the Silvermoon (novel/manga). Given that some black-rank jobs include babysitting and manual labor. in the extra materials The twins are considered prodigies of their village whose first feat is wiping a goblin nest with a hobgoblin. If the crystal deer had any power, it would make sense that the difficulty is way above the black rank thus a desirable price.

• How does Endemyion learn languages across worlds?
  • Since his race has the inherent ability to travel between worlds, it would make sense for them to also have the latent ability to communicate in any language.

• In the anime, the butler Leim traveling alongside Sushie gets shot with an arrow, but no enemies, even the mage himself or his subordinate Lizardmen summons, use a bow/crossbow, so how the hell did the butler get an arrow stuck in his chest...? The abridged series made by the Youtube channel "Yusho Productions" even lampshades this oddity as well.

• Mithril inflation? The Western continent appears to have no use for mithril due to it affecting golems but the Eastern continent prices it as a material for its strength and magical properties, would the Western continent be willing to sell there's to the East?