Traits are a great idea in theory - a couple of "half-feats" that you pick at character creation to add a minor bit of customisation to your character and also give a few role-playing hooks.I loved pathfinder and I think they came up with many good idea. But when they game got so complex that we were using hero lab to create characters we quit. They keep adding layers of complexity like archetype (different than 5E) and traits and I can’t remember what else.
Of course, this being Pathfinder it was implemented in as complicated a way as possible.
Lots of categories of traits, including the Basic category which was split into 4 sub-categories, and you couldn't have two traits from the same category, except that for Basic ones you could have more than one so long as they were from different sub-categories (I have absolutely no idea why the sub-categories weren't just made into categories and the Basic part just ditched).
A category called race traits, which is something completely different to "racial traits" (which are what you get as your racial abilities per the races chapter). Then you get the "adopted" trait which allowed you to get the race trait from another race, making the distinction moot but also making people think they could get racial traits with it, such as stonecunning or darkvision. But you could in theory get things like a halfling brought up by orcs being able to get a bite attack or a very ugly (and therefore intimidating, since this is D&D) face.
And of course the rush to create as many traits as possible, so there are literally hundreds to choose from, some of which are objectively better than others (e.g. granting a +2 instead of +1), some of which are exactly the same as others but in a different category, and some of which are exactly the same as others and in the same category. And many of which are either useless in themselves or useless except in very specific circumstances that almost never happen.
And campaign traits, which are flat out better than other types of trait to reward you for picking something campaign-appropriate. But which are lumped in with all the other traits if you do a search on Archives of Nethys, so you then have to explain to your players that they can't pick those unless you are playing a specific campaign.
But technically one of your traits has to be a campaign trait, so are you going to design some for your homebrew?
And, of course, there is a feat to get extra traits. Which you can take more than once.
And "exemplar" traits which count as two traits (so how does that fit in with the requirement that one of your traits is a campaign trait?) which allow you to ignore the rule about no more than one trait from each and actually gives you benefits the more traits you have in a specific category.
And absolutely no guidance as to whether NPCs get the free traits or not (I just give them to NPCs as needed, but usually only one rather than two.)
And traits give trait bonuses, so they don't stack with each other but do stack with everything else. Everybody involved in Pathfinder was crying out for a new type of bonus to go with the hundred it already has.