tabletop RPGs & worldbuilding: my players will never see 90% of this and that's fine

I DM a campaign. the campaign requires, apparently: three hundred years of fictional history, a functioning tax system, tide tables for a fictional coast, and (see the conlang thread) a language. my players interact with roughly a tenth of it. the iceberg is not for them. the iceberg is for ME.

thread for: DM prep as a special interest, homebrew systems, worldbuilding rabbit holes, and recruiting — if anyone here wants a slow, sensory-friendly, text-based campaign, I am absolutely reading this forum thinking about party composition

"the iceberg is for ME" should be on this site's banner honestly. and: text-based, no voice, no time pressure? that's the most accessible pitch for D&D I've ever heard. tentatively raising a hand.

ok yes. if the system has rules I can learn ALL of them. what's the tax system though. genuinely asking