I was using a standard cheap 150mm X 1200FL Celestron Refractor in March last year. Being an achromat there was a huge amount of chromatic aberration.(CA) Here is what I found visually:
with 7mm eyepiece (X171) Sirius B was intermittently visible, with 5mm eyepice (X240) it was constantly seen, and with 2.3mm eyepiece (X522) it was very easy. I have a few not very well tracked, but quite distinct images. (I intend to take some better ones.) (Viewing from Brisbane, Australia. 27.5 deg South. 153 deg East.)
Regarding the Dogons’ knowledge, skeptical analysts indicate that the Dogon’s knowledge may have been contaminated by the researchers who were conducting their research shortly afterwards, as the information provided by the Dogon priests corresponds with European knowledge of the late 1920’s. Check it out with Mr Google.