I think you´re referring to how goblins are depicted in past editions. That is not the case anymore. You find goblin villages and a goblin merchant in several adventure sets of the FR setting or even in Chult. And yeah, all goblins speak goblin and common.
I do not expect them to speak with the diction of a news anchor either, but they speak with a very informal heavy ¿cockney? accent. No stranger than dwarves speaking Scottish.
They are usually evil and raiders or scavengers, yes, but they are not mindless babbling creatures without social ties. In fact, the goblins have strong social ties with his tribe and a particular social structure.
Goblin society was tribal by nature. Goblin leaders were generally the strongest, and sometimes the smartest, around. Goblins had little concept of privacy, living and sleeping in large common areas; only the leaders lived separately in their own private chambers. As such, goblin lairs were often stinking or soiled, though easily defended when under assault.[9] Many such lairs were layered with simple traps for such purposes.[17]
Young goblins were taught from an early age to rely only on themselves and that to survive, they needed to be aggressive and ruthless. To a goblin, it didn't seem logical to treat others as well or better than you would treat yourselves; rather, they believed in preemptively removing potential rivals before they could become a threat.[9] Because of the violent nature of goblin culture, it was not uncommon for goblins to come under the domination of individuals from a larger, more physically powerful culture, most typically larger goblinoids such as hobgoblins or bugbears.[8]
Goblin settlements were typically very densely populated and filled with young goblin children. This was in part because goblin females were expected to birth as many children as possible to sustain a population constantly driven down by violence. However, young goblins did not outnumber adults as their lives often were at least as dangerous as those of the adults.[9] The innermost chambers of goblin lairs were usually the most densely-populated and well-defended.[15]
Male goblins, who were dominant in goblin society, sustained the community by raiding and stealing, sneaking into lairs, villages, and even towns by night to take what they could. If supplies got short enough, goblins would even resort to eating members of other races, including other goblinoids.[9] Some goblin tribes were not above waylaying travelers on the road or in forests and stripping them of their possessions.[18] Goblins sometimes captured slaves to perform hard labor in the tribe's lair or camp.[19]
Religion
Following the Spellplague and prior to the Second Sundering, however, the power of the Black Lord Bane grew and extended his power over Maglubiyet, making the goblin god one of his exarchs.[20] Following the Second Sundering, goblins again worshiped deities such as Maglubiyet and Khurgorbaeyag.[21]
There are examples of drows worshipping Elistraee, like Solaufeinn or Drizzt that worships Mielikki, There are lots of exceptions of characters worshipping gods you do not expect.
I think that was the typical "Journal of a dead person telling a story" you find everywhere in rpg games and a colourful way of indicate the player that the underdark is up ahead and a reason to have spiderweb boots in the corpse. I do not know why a high elf captured by drow could not lost his mind and develop Stockholm syndrome and started worshipping Lolth instead.
So no, no out of place in the way FR is in 5e, at least no more than usual.
