Hi, the pto shaft is unguarded yes. Its an easy matter to fabricate one if you want to use the machine for trailer work, most folk will have an implement mounted much of the time though. Grey import shouldnt put people off purchasing a machine, I dont advocate unsafe practice and would assume folk know what they are doing in the first place, if they dont they should not be near any machinery. I have seen some terrible practice locally, usually horsey folk with front loaders who should know better! The courses are there at local ag colleges, if not get instruction from another smallholder or farmer.
Yanmar have been making diesel engines for over a century and small Japanese tractors are the best in the world. The offerings from China are pretty dire. Anyone building a flatpack tractor needs to be very competent and these machines have a CE mark! Dont forget the CE mark is as much to do with emissions as safety. Bottom line is, tractors are dangerous bits of kit, but then is a car or a food mixer. The answer is "do what it says on the tin" and you wont come to grief!