It's perfect, well done!
What confused me at first was the upside down printing. But once I detected the compass rose it became clear that the original sheet wasn't north-up, as you said.
The tile identification is very much standardized. And it's rather straightforward. Tiles are simply ordered by number, starting with 0 at each zoom level, then increasing in easting and northing direction. Origin and axis orientation may vary, but that's minor detail. In our case here, the only slightly unusual thing is the reverse order of column and row.
In your example, the tile is the 4798th in the easting direction and the 6246th in the northing direction, at zoom level 14. Northing is actually a southing here, as the axis is inverted. (It's plus 1 for both axes, as the numbering starts with 0.)
The fundamental idea lies in features of the Mercator projection. If you restrict the latitudes to about 85 degrees north and south, you can map Planet Earth to an exact square. They made it a unit square, with a projection coordinate range from 0 to 1.
For zoom level 1 you will only have two tiles in each direction, for zoom level 2 there will be 4, then 8, then 16 and so on. With the inverted northing or y axis we look at the north-west corner of each tile. For tile [0,0] at each zoom level, the Mercator projection coordinates will also be [0,0]. The north-west corner coordinates for tile [1,1] at zoom level 1 will [0.5,0.5] and [0.25,0.25] at zoom level 2.
Once you have the projection coordinates you apply the (reverse) Mercator projection and get latitude and longitude.
So, the entire geo-referencing thing is rather implicit for map tiles, as it completely relies on the tile numbering scheme. Nonetheless it's well defined and precise.