Greasy Fork is available in English.
Adds: sidebar toggle bar (click on blue vertical separator bar), auto collapsing sticky floating table of contents at top left (hover mouse on it to expand), collapsible sections (click section title to toggle), section links (for getting URL to page sections), auto popup sticky table headers (when table height is longer than the screen), table manipulations (double click empty space of a table cell to show menu).
YES! This is *exactly* what I've pined for ages to be able to modify Wikipedia on the user's-side with, no more/no less. You're a saint IMO bc this is one of those things I've spent an absurd amount of time seeking out a pre-fab script for as a result of my willful ignorance towards learning/retaining any useful knowledge about writing code, and Wikipedia's obscene amount of whitespace has been testing my resolve for years now... Not anymore: Status quo successfully maintained!!! Lol