STC appears to be a company not willing to trade with the english-speaking world, and I have seen no english material from them so far, although they appear to have an interesting line of products, including (but not limited to) '51-derivatives, and not only of the "vanilla" type, but also some very interesting '2051-pin-compatible singleclockers, too.

However, the fact alone, that they don't publish english datasheets, IMHO does not substantiate your assertion at all. But if you have more evidence for that except the lack of english documentation on the web, please let us know.

JW