What is the function and purpose for the restriction bolts on the transmission?

They are there to prevent the shift forks from moving to far by stopping the shift selector under the cover when it hits them are not adjustable. They are simply hardened bolts torqued in place to stop the shift rail head. The common problem with that transmission is the tip of the shift lever and the seat that goes into the top of the transmission wearing and then you get hard shifting and it pops out of gear. Both are easy to repair by removing the trim and the 4 screws from the shifter boot then you use your fingers to push down and counterclockwise to remove the retainer then pull up on the shifter. Under it you will find the socket it sets in, they wear and can crack, also the piece on the end can break as well. Both are replaceable. If however they are tight with no play then it may be that you have a bent or cracked shift fork or damaged shift rail. The forks are somewhat easy to damage if the lever gets hit while in gear. They also wear if anyone tends to drive with a hand on the shifter.
What is the problem you have?