Usually when its hot to touch - and 70C is quite hot to touch something is not right - I mean we are talking about a lathe head stock - plain bearings when something is "off" can get hot. But I never had bearings that are not plain get even past "warm to the touch" - so maybe 40C after running for 10h.
Now look at transmission case in a car - technically 70C should be still OK, even up to 100C - so bearings in there are OK at that temp. But we are not talking about car transmission but a lathe -
I.e. Chinese can be technically correct - it can get hot without damage but in real life, for the machine type, they never should be even close to this hot.
Same for my milling machine - maybe 40C, maybe 45C. But never so hot I could not hold my hand on the housing for however long I wish.