The serial number area was deliberately left blank. If someone wanted an even closer resemblance to a G36 they would then be free to engrave their serial in the blank. Most people would not care, but maintaining the option was the decision. If something else was molded in that place then I can only imagine the disappointment it would cause.While I agree with the majority of that statement, I think it does not really apply here. A G36-clone is not a first-time buyers' gun. I imagine the vast majority of T36s (and future TG36s) have never seen hard use and never will due to the 'grail-gun' nature of it. Everyone in this thread knows why the ATF targeted this weapon.
That said: the problem with the data plate should not be the layout, but rather everything else. ehunt's first picture (in Post #24) is unedited. I had hoped that under the "Cal 5.56mmx45" line there was a serial number - as seen on the real HK. I assumed it was edited out in the picture, but it is actually not present on the receiver. The legal serial is still in the same place as it was on the T36. Towards the bottom of the data plate, the proof mark adds some interesting connection to the original, but it just hovers in the void without an engraved serial number.
The more interesting issue is the polymer flow as the receiver was molded. The matte dark area under the "Cal..." line is very noticeable and almost exactly the same on mine. With an engraved serial number, it may not be as obvious.
Does any of that matter? No, but in comparison to the destroyed T36, it is different and apparent.