It isn't. There are only a few dozen intragalactic novas per year. They've been looking for this one for a while and so far this is the only candidate anyone's found.
one can now draw _many_ star trajectories through groups of novae each caused by a single star?
That's a bit like saying you can draw many trajectories of cars that could have been in a crash while the smoldering wreckage is sitting by the side of the road.
Their conclusion in the OP was AIUI that _many_ stars produce novae serially. So we should surely be able to match series of novae (along a stars trajectory).
Do you know are English language details of the historic Korean record available (are they in the paper)?
http://www.cbat.eps.harvard.edu/nova_list.html shows very few recorded novae, is this a listing including the dozens per annum you mention?
The time between classical nova outbursts is estimated to be on the order of 10,000 years, so the previous outburst of this particular nova was probably long before the development of writing.
In addition, it likely takes only a couple of thousand years for the expanding shell of gas to fade from visibility, so it's probably not possible to find the traces of previous outbursts along the trajectory (although that would be cool).