The Lanshan tents are made by 3F Ultralight. I have a 3F UL hex tent that uses the same silicone outer/PU inner fabric used on the Lanshan. This fabric has a generous silicone coating that beads water nicely; the inner PU coating is rather thick, which provides a high hydrostatic head but probably results in poor tear strength. That said, the overall impression I have of the fabric is that it is high quality, although the heavy coatings result in fabrics and tents that are a little heavy. From what I’ve seen, 3F UL quality and sewing is very good, maybe equivalent to REI brand tents, maybe a little worse, hard to say; however, the designs and details are not as refined. For example, the Lanshan 2 is certainly a nice little tent, but it’s short, has very small vestibules and there is no way of knowing at this point how long that fabric, which appears so adequate from where I’m sitting, will last before tearing or delaminating. No warranty, obviously.
Chinese tent makers exist in a quality hierarchy. From what I’ve heard from Chinese outdoor shops, from best to worst, they rank: NatureHike > 3F UL > ASTA Gear > Knot (aka Ice River) > various rubbish brands.
As Mole said, ASTA uses double-sided silnylon that is decent quality. There are quite a few reviews of models made by the first four companies on various forums and on youtube. The German Ultraleicht website is paticularly information rich – run it through Google Translate and watch for posts by “Wilbo.”