Those engine mount bolts are called studs and they are meant to be threaded on both sides. With that said, their quality is less than what is available in the USA and you should replace them with non-Chinese made ones.
I get my all thread rod from True Value hardware.
I also use replacement metric bolts (from Lowes or Home Despot), usually allen head ones, that are longer than the studs and use them as studs with locknuts, washers, and of course loctite. The allen head ones are black and blend in nice on the exhaust and intake manifold.
I use blue loctite all of the time. To undue blue loctite, all you have to do is hit it with a torch for a few seconds and you can unscrew your bolts/studs.