It is not just Kioti loader bolts.. ALL loader bolts back off for a period of time. You should check torque when you get the tractor, then at 25 hours, then every 50 hours up to about 150 hours, You will find that as time goes on they don't loosen up. A lot of guys mark the bolt heads to keep an eye on it. By bearing box, he means the upright pillars to U channel steel the ends of the loader arms "bear" into. These are bolted to the tractor itself. Designs vary. The larger bolts are somewhere around 160 ft lbs, some less. You just need the loader manual (Dealer gave me mine) and tighten per spec, or get the size of the metric bolts and look up the generic bolt torques for that size of bolt on the internet. Locktite is not a bad idea. I had a lot of the little bolts that hold in the greased pins that kept getting loose. I used red locktite on them. Also check the wheel bolts on the same schedule. If you don't you wheel bolt holes will "egg" out, and be ruined.
If you read old threads on here, many different brands have suffered from bolt neglect, by snapping off the bolts leaving pieces in the tractor or even busting out the castings.