My suggestions were not meant to change the mystery chests at all, but to only alter the chests in the third tier by removing the spell fragments in the gate chests and replacing with the three items suggested, one item per gate. The percentages of the added items could be adjusted if necessary but were close to the original and thus, I think, acceptable as replacements.
As for the mystery box changing from 30%. 30%,30%,10% (if that's the one to which you refer) to 50%,20%,.20%,10%, that just increases my belief that the changes would work. A 50% chance of getting teleport spells rather than a 30% chance is a very good improvement, in my opinion.
That's my take on it anyway.