If you can define the traits in "trees" then the pedia code that shows the unit and building upgrades can be used to display the trees. If they are all "individuals" then that wont work.
They are straight stalks. For now, according to the design, you'll have 3 tiers for each trait. IF you play without developing leaders, the traits will individually be stronger than they are with it on. But if you collect all three of one type, it's pretty powerful in the end, but then you have also trippled up on the downsides too and in most cases that can get pretty painful. You can alternatively get a little of a lot of different things and look for the synergies there. There WILL be tech prerequisites for the second and third tiers and numerous benefits are tied to the mid or late game for 2nd and 3rd tier traits, so taking a bunch of 1st tier traits will tend to have you missing out on some benefits that apply during the stage of the game you're in. It can also be possible to earn traits too quickly which forces you to take more Tier 1 traits than would be optimal, making it much harder to then earn the later Tier 2 and 3 traits.
We can always have specialized combination traits thereafter but I have a LOT of basic trait selections, I mean a hell of a lot. So I don't think we'll be lacking for options.
I find with the current trait structure that you tend to go for the same traits because they aren't very well balanced. These have been balanced to a very fine measure to the point I cannot, myself, see which would be the best picks, and even if I did I'd want to play more games to explore more of the options available in terms of blending different ones. And the option between diversity and specialization will always keep you guessing which would've been the better pick.
If you are playing with Developing Leaders there needs to be more feedback eg a bar like the tech bar showing how close you are to getting the next one. Perhaps a screen like the Tech Screen for selecting your new trait so you can see where you are going.
We have that, not in a bar but the measure of how close you are and what you have yet to earn to get to the next trait selection and how many traits and which traits you've earned so far is all displayed on the flag hover. Would take one of you python guys to make a progress bar display.
Currently in C2C there seem to be overlapping sets of traits in the XML and figuring out which belongs where is impossible
There are.
1) a core set for non-developing leaders, which currently is identical to
2) a core set for developing leaders
3) an option set (Focused Traits) by ls612 for non-developing leaders, which is also identical to
4) an option set (Focused Traits) for developing leaders
These sets did not attempt to differentiate for DL but the traits need to be defined differently for each so they are currently just copies. The intention was always for the DL set traits to not be as strong so as to allow a more gradual progression into trait delivered powers and benefits.
There had been some disagreement between AIAndy and I on how these should display in the pedia. I wanted them all visible only if a game setting wasn't defined but if options were selected by default or a game was in progress, only the applicable traits would show up in the pedia. He disagreed and I feel his results are a bit confusing to look at.