Based on naming conventions used in VCDS, diagnostic tools, or open-source projects (like EDIClient, python-vagcom, or MQB tools), eewritelang would likely be a function to in an ECU (e.g., instrument cluster, MMI, or gateway) on VAG vehicles (Volkswagen, Audi, Seat, Skoda).
It looks like you're referring to a feature or command related to (now known as VCDS from Ross-Tech), specifically something like vagcom-eewritelang . vagcom-eewritelang