Do you mean nothing was damaged and they still charged as before from utility power?
Or that after some fiddling, it started working via V2L from one car to the other?
If the latter, what "charger" did you use? An EVSE (AC "charger") is supposed to do some sort of earthing check, and if that test fails, it's supposed to refuse charging (not turn on its internal relay to connect AC to the Type 2 plug). I don't know the complete details of that test, but I can't see how a V2L could pass that earthing test.
I tried using V2L to charge my ZS EV, and it didn't work. After being initially puzzled and disappointed, I decided that both EVSEs that I tried (MG and a Chinese one) were failing the earth test. Sadly, unless I missed something, neither EVSE told me (via LEDs, since neither has a display) what the specific problem was.
My assumption about the EVSE earthing test is that it looks for a consistent low voltage from neutral to earth, possibly after injecting a small current. If as I suspect the V2L neutral is floating with respect to the vehicle chassis, this test would fail.
I wonder how the earthing test is done in North America, where 240V is actually two out-of-phase 120V "hots" with respect to earth. Maybe they check for approximately 120V AC from "neutral" to earth first, and check that pushing it with a small current doesn’t change the voltage significantly.