The amount of barrier provided by Temerity Unique pants remain unchanged even if you slot maximum life gems into your gear. Is this intentional? In the character tooltip, under the Defensive section, there is a stat called “Maximum life” that increases with gems, and Temerity also mentions maximum life in its tooltip.
Same goes for barrier generation gems unless I have misunderstood that functionality: Barrier from Temerity does not increase when barrier generation gems are equipped.