sorry, I was ribbing and a little buzzed last night. tried to denote that with smiley.
I have no affiliation with Titan, just like the product.
Bummed that you are getting air balls from post bumpers. What game in particular is this on? It seems to be largely feedback isolated to you/your game. IME when I get airballs on any game, more often than not it starts at the flipper and I find that a flipper rubber is either slightly too high or too low on the bat itself. Have you checked to see if the titan 1/2" post sleeves sit in the identical up/down position where you are using them? Sitting even a 1/16"inch lower can quickly cause lots of air balls.
Aside from that I would be surprised if the durometer/bounce is much different on titans from the black rubber fatties. You could do a simple test of making a board with side by side post sleeves and do a drop test to see the rebound height of a ball changes much w the sleeves. Small differences could also be coming in if the sleeves are not fitting as tight and changing the physics.
Maybe email directly with Titan and see if they have any thoughts or tests on this.