The comments so far seem to indicte a wide range of satisfaction with imported bits for a mortiser; ranging from rather complete satisfaction to the opposite.
One very large problem with imported items made of metal is that, while it is easy to check for appearance , it is far more problematic to be sure that the maker consistently employs the right "metalurgy" technology and raw materials - the processes that assure that metal parts end with the best physical properties - because it is more or less invisible, and we are in the habit of trusting that manufacturers have knowledge of this which they incorporate in their tools. It is the assumption that the manufacturer employs the appropriate steel and best processes that enabled once famed manufacturers like Stanley or Buck Brothers in the old days to build strong reputations which have made some of them the gold standards, for chisels, planes, carving tools, etc.
With tools from "virtual" manufacturers, it is not possible to tell easily which ones manufacture to the best prac tices, and with consistent quality.
I believe this explains the wide varierty of experience. You may have wonderful luck with import, or you may not.
Karl