The armor has a lot of squishy bits... and the armor you're using looks like the stuff that'd be for the general field combat rather than strictly mounted. Too many gaps and not solid enough.
The biggest distinction between combat armor and jousting/tournament armor would be the added layers of protection for different activities at the tournament. In this case, the helmet you have is generally right but the rest of the armor is begging to be punctured.
Example of jousting armor.
Example of combat armor via a manuscript.
Example of jousting armor from the same author.
Notice the lack of a shield on the shoulder and less overall "bulkiness". That's cuz folks who did the tournaments were competing using a very specific suit per activity that optimized protection and let them do ONLY what they needed to do. They weren't expected to hop out of their horse after they lanced a dude and shank him on the ground. Also those that did tournaments were mad rich and could afford a separate suit of armor per event.
In terms of jousting in general, in the tournaments you never hold the lance out the whole time and forcefully aim with it. Instead you gradually lower it until you get it where you need it to be right before impact because this will lessen fatigue in the arm and actually grants greater accuracy. So possibly adjust the jousting to a distance/leveling mechanic. Not only that but most armor also has a slot that's used to actually hold the lance as shown in the following images.
The first armor looks as though it could be used outside of just jousting like actual combat whereas the second armor looks exclusively for jousting. Maybe have suits of armor that buff characters ability to use a lance better?
Or, maybe, set it so that when jousting, those with inferior armor have a harder time of setting the point where it needs to be, as though they need to do the lowering technique as I mentioned as the only way to lance someone, whereas somebody with the right equipment have the ability to hold the spear and place and have a better chance of putting the point where they want it. Allow certain mechanics to be bypassed by technology?