OK, this is the sentence in question:
The sun has also another motion by which it revolves round a grand center called Vishnunabi, which is the seat of the creative power, Brahma, the universal magnetism. Brahma regulates dharma, the mental virtue of the internal world. When the sun in its revolution round its dual comes to the place nearest to this grand center, the seat of Brahma (an event which takes place when the autumnal equinox comes to the first point of Aries), dharma, the mental virtue, becomes so much developed that man can easily comprehend all, even the mysteries of Spirit.
Now, there seem to be two revolutions, one around the sun's dual, the other around the grand center. No details are provided. Also, Sri Yukteswar does not describe the location details of Vishnunabi. It may be a grand center astrally speaking, that is a hub of spiritual radiations, in an unspecified location in the galaxy. It may be the center of all the galaxy, but it is not specified.
OK, now one issue is the revolution of the sun (and its dual, probably) around the grand center. Does the binary system revolve around Sagittarius A*? That's a positive, all the stars in the galaxy rotate around the galactic hub.
So, the point which satisfies this requisite (a point around which the binary system rotates) is probably Sagittarius A*.
One problem with this interpretation is that the difference in the galactic perihelium and aphelium is relatively little, so it is not very reasonable that such a small delta-distance relative to the galactic radius may influence so much the mental virtue.
But then, we should demonstrate that the sun binary system rotates around some barycenter different than the galactic hub....
