Converting ingame coordinates to real life latitude and longitude

I need to convert in-game coordinates from the game Euro Truck Simulator 2 to real-world geographic coordinates. The game uses a coordinate system in meters with a scale of 1:19 compared to the real world, where coordinates 0 0 is approximately in originRealCoords lat and lng. Game provides a map of whole Europe.
The problem is that the longitude and latitude become less and less accurate as the point moves farther away from x: 0, z: 0. Maybe there is another way to convert in-game coordinates into real-life coordinates?

function convertGameCoordsToLatLong(gameCoords, originLat, originLong, originGameCoords, scale) {
   // Convert game coordinates to real-world meters
   const realX = (gameCoords.x - originGameCoords.x) / scale;
   const realZ = (gameCoords.z - originGameCoords.z) / scale;

   // Distances in degrees on Earth (approximately)
   const metersPerDegreeLat = 111320; // Average distance in meters per 1 degree of latitude
   const metersPerDegreeLong = 111320 * Math.cos(originLat * (Math.PI / 180));

   // Convert distance to degrees
   const deltaLat = realZ / metersPerDegreeLat;
   const deltaLong = realX / metersPerDegreeLong;

   // Calculate new coordinates
   const newLat = originLat - deltaLat;
   const newLong = originLong + deltaLong;

   return [newLat, newLong];
}

async function getCoords() {
   try {
       const res = await fetch("http://192.168.0.106:25555/api/ets2/telemetry");
       const json = await res.json();
       return { x: json.truck.placement.x, z: json.truck.placement.z };
   }
   catch (error) {
       console.error(error.message);
       return { x: NaN, z: NaN };
   }
}

async function convertCoords() {
   // Initial data
   const originGameCoords = { x: -5.121521, z: -14.6748238 };
   const originRealCoords = { lat: 50.746475, lng: 10.508655 };
   const scale = 1 / 19; // Ingame map scale

   // New game coordinates
   const gameCoords = await getCoords();

   // Convert coordinates
   return convertGameCoordsToLatLong(
       gameCoords,
       originRealCoords.lat, 
       originRealCoords.lng,
       originGameCoords,
       scale
   );
}

convertCoords();