It's very strange, all the model number searches return no results, must be a very custom job. It's possible if iFixit looked under the label or otherwise (safely) took it apart they could find further markings.
I had some Chinese friends look at the characters, and it's the exact same as the English, so no hidden numbers or signatures there.
I'd say not Samsung since it's Chinese, and by the same logic not LG (neither has manufacturing centers in China), so I'd look at Foxconn (known to manufacture kindle parts, manufactures most computer parts in the world) or maybe Quanta (Taiwanese company known to have worked with previous kindles, has a lot of Amazon/RIM overlap dating back to the original kindle, in light of the similar hardware between playbook and this, I think it's likely [speaking of which, iFixit should teardown a playbook, would be an interesting comparison]). It's worth noting the labels all say "China" not necessarily PRC or ROC, so we can't rule out Taiwan.
edit: looks like there is a playbook teardown, I'll try examining the two images.
edit2: Ok, primary analysis says they look suspiciously similar, as in, same manufacturers, (it was done by Quanta), warnings and symbols are identical and verbatim, the model numbers and barcodes look very similar too, the only difference is the capacitance.
edit3: I'm gonna go ahead and call it for Quanta