not all events are a 100% reliably logged. With that you can forget said "proof", because no log entry does not reliably equal no in game event. Use some common sense.
A flight with a missing rudder and no damage from bullets recorded is a lot more proof than "I think there is something wrong", which is all the proof he's provided so far. On the other hand, if you receive damage from enemy (or friendly) fire every time you lose your rudder, that's pretty strong evidence that the rudder is being shot off. In other words, use some common sense.
BSR, I don't believe you're correct regarding the log.
Here's a brief snippet from our Wargrounds server C&P'd from the Stats Page (I've
only removed the pilot names from each line)
12.09.2014 07:50:30 [Halberstadt CL.II 200hp] was respawned
12.09.2014 07:50:32 [Fokker Dr.I] was respawned
12.09.2014 07:51:30 [Fokker Dr.I] take off
12.09.2014 07:51:31 [Halberstadt CL.II 200hp] take off
12.09.2014 07:57:02 [Halberstadt CL.II 200hp] was respawned
12.09.2014 07:57:48 [Fokker Dr.I] has destroyed AI [Caquot]
12.09.2014 07:57:51 [Halberstadt CL.II 200hp] take off
12.09.2014 08:01:18 [Fokker Dr.I] was disabled
12.09.2014 08:01:26 [Fokker Dr.I] crashed on the ground
12.09.2014 08:01:44 [Fokker Dr.I] has finished
12.09.2014 08:06:47 [Halberstadt CL.II 200hp] has killed AI [BotGunnerHP400_3]
12.09.2014 08:06:48 [Halberstadt CL.II 200hp] has killed AI [BotGunnerHP400_2]
12.09.2014 08:07:27 [Halberstadt CL.II 200hp] has killed AI [BotGunnerHP400_1]
12.09.2014 08:08:42 AI [Turret Halberstadt CL.II 200hp] has shotdown AI [Handley Page 0-400]
It's pretty sparse - and gives little (if any) indicator *why* something happened.
For instance, note in the middle of the log about the DR.1 "disabled" and "crashed".
There is no information about how or why it became disabled and crashed - did the
pilot crash into the balloon, oil the engine, break a wing, screw up a landing???
I can't see how this would help with identifying a so-called "glass rudder" situation
either, as it wouldn't be definitively stated in the log.
Now, the logs in the actual server "might be" more detailed (I *don't* know that for
certain as I've never looked at those), but even if they are, a typical player wouldn't
have access to them unless they're running their own server.
As for the actual OP issue, my purely subjective feeling is that there is something a
little odd with Nieuport rudders compared to other scouts, but I have nothing to prove
whether it is actually different, actually a bug, or just a quirk of Nieuport design.
Whether it should be looked at or not would be solely up to the devs (barring any definitive
proof of a bug).