(final round of Lünenberg lore, also cobbled together from old posts/discord conversations)
Because Lünenberg was founded out of necessity during a war by followers of different gods living in different sub-regions of the area, there was no unified language for its early citizens. As such, modern Lünenbergish is a creole between two different languages at that time, with vocabulary from others. Literacy is high and things like spelling and grammar are very standardized. However, though the component languages that were spoken by the early peoples that made up Lünenberg are no longer living languages, and are only known by scholars and linguists, they do still influence the modern language in terms of pronunciation and accents.
Regional accents in Lünenberg are typically quite pronounced and are stratified both by region and social class. A Lünenberg native can usually tell within a sentence or two approximately where another speaker is from, and generally what their upbringing was like. Because of these regional differences and a desire not to privilege institutionally one interpretation over another, the country plays loose with 'official pronunciations.' For example, Nikolette pronounces the nation's capital of Kathédrale as "kah-tay-drah-luh" while someone from a different region or socioeconomic class might pronounce it closer to "kah-thay-drull." Names for people can be similar. The 'tt' in Nikolette's name are aspirated consonants, but whether they would be pronounced as such without her saying so or introducing herself first depends on the speaker.
A curious result of this national quirk, with loose pronunciation rules but very strong grammar and spelling rules, is that citizens develop a strong written voice, and place a higher emphasis on the written word than most. Reasonably high-quality papers and inks are available at every price point, and it's expected that most families keep them both in supply. The national courier system is very reliable, and it's common for friends even in the same town to exchange letters relatively frequently. There's an old-fashioned sentiment that a friend or lover who prefers only to speak has more interest in hearing their own voice than either understanding or being understood (Nikolette writes often, but she absolutely is levied with this critique from time to time.)
There are many holidays in Lünenberg. Some are regional, some of them shift in the calendar (the reigning Empress/Emperor's birthday, for example) and others are declared year-to-year by either the Empress or the Church. There are, however, three national holidays that can be marked upon a calendar ever year at exactly the same points.
The Sacréelicht Festival is much beloved by working-class citizens for it runs five days straight in the mid-summer, granting a welcome reprieve from labor. The festival honors the gods of light who helped save the nation from the elemental titans, and involves a number of events such as public feasts, games, and large art demonstrations involving candles, torches, or magical light.
Vaincresprit is an autumn holiday that reenacts the war that led to Lünenberg's founding. Theater troupes act out scenes of battle, while children dress as elemental beasts and are playfully bribed with pastries or sweets to take their mischief elsewhere. It's said that the monsters of Lünenberg stir at this time of year, and soldiers, hunters, and students at the Royal Academy are dispatched to defeat any that pose a threat to the people.
Schwurgießen is a winter holiday where the citizens celebrate the covenant sworn between the first Empress and the gods of light, by swearing oaths to each other. Historically, people of means would cast these oaths in as bronze tablets, but that has long-since fallen out of favor. Instead, people of all classes write each other letters (often with special Schwurgießen-exclusive expensive ink and paper), making promises and swearing to uphold them. These can be quite lengthy, and one is expected to write many of them. In Nikolette's case, she probably writes about a dozen letters each year between family, friends, her friends' families, and her fiancé, most of which run at least four or five pages.
In order to encourage them to take their oath-casting seriously, children are often given gifts if they've lived up to the previous year's oaths, though this is largely a formality and nearly all children receive gifts regardless of their behavior. Recently, it's become fashionable for young adults to exchange Schwurgießen gifts as well, in addition to their letters, particularly among close friends or romantic partners.