Just got an email from Fitear about my MH335DW (in japanese T^T). From my little knowledge in japanese, google translate, and japanese assistance professor in mechanical engineering that sit next to me, this is their response.
The say that the "crack" that I mention is not actually the "crack" but is the interface between their acrylic shell and the resin that they used for filling up the shell. They measure the distance from the tip to the "crack" location and confirm that those 2 mm from the tip is actually the thickness of the acrylic shell of the stem. They said this could happen and won't effect the performance of it.
I also wrote back to them informing about other fracture that I found on both stem and waiting for their reply.