>>3405429That picture you linked shows a clear asymmetric design.
A symmetric design has the same behavior of rays on both sides, with only the scale being different. Naturally, this means same, or very similar layout of elements in front and in the back. However, the term is being used quite loosely nowadays as almost no modern lenses are fully symmetric due to corrective elements included.
The term "telecentric" academically means that the image circle is the same size regardless of where the lens is focused, with the main rays exiting the lens at a 90 degree angle. However, it's used loosely to mean any lens design where rays hit the sensor at close to 90 degrees; I'm pretty sure actual m43 lenses aren't truly image-space telecentric, and they don't need to be - the sensor can still handle light hitting it at a couple dozen degrees off perpendicular.
So if you imagine a symmetrical telephoto design, the rays come in as a narrow cone in the front, and must exit as an equally narrow cone from the back. Since the cone is narrow, the rays will hit the sensor close to perpendicular, thus close to how it happens on a telecentric design, and there won't be a problem with vignetting.
