"They should have been able to get that from our transponder." says Logan.
Note: They do seem to have a transponder, but so far your system isn't making sense of their transponder signals.
What you have picked up on sensors is compatible with their being a 200 ton vessel and seems to have a signature that would match what your library program shows for a Vargr 200 ton Trader. The library program doesn't have anything to say about indecipherable transponder signals.
Oh, and I should also add that the library program makes no mention of Vargr in this corner of space... The known Vargr are actually almost clear across the Imperium...
"Vargr where they shouldn't be with a transponder outputting what looks like gibberish in an already pretty suspect non-Imperial system. This is certainly interesting!" Logan says, "But interesting can also mean dangerous, so let's be careful with these folks."