I'm aware for over 100 years the reason has been known how impact craters are almost always circular, but my question really is has there been any recent insights in the area? What other topologies are physically possible?
There are elongated craters from grazing impacts, and these can sometimes get rather odd shapes like Schiller on the Moon and Orcus Patera on Mars (the later is a bit contested, it might have formed from something other than an impact).
Double impact craters is another possibility. Some craters occur simultaneously (more direct picture). Splitting impactors is likely the one way of getting truly complex topologies. Most of the time they tend to follow each other, producing crater chains.
If terrain shifts craters may be deformed, and depending on details in the rock they may also get odd shapes. Meteor Crater in Arizona is somewhat squarish.
Craters cannot generate that complex patterns since they are just explosions out from a center and impactors are usually single objects or random clouds. In principle one could arrange asteroids along a trajectory to spell out letters upon impact, but it is an exceedingly unlikely configuration so most impacts will only manage 'O'.
Impact craters are not always circular. They vary based on the angle of incidence.
One example is the Wetumpka crater. There is also research on Asymmetric craters on Vesta: Impact on sloping surfaces which states e.g.
The global occurrence of these crater classes compared with a slope map clearly shows that these asymmetric crater types exclusively form on slopes.