Don't edit traits, just don't, please, spare yourself.

(possibly this only applies to mods that don't use traits to link in with the campaign scripts, but I wouldn't guarantee it. It is ubleviable what one tiny little trait change can do to an eb campaign, for example)

As to the other I had always thought that that tax line was a modifer, so you could make some settlements richer in taxes, regradless of population, but its a while since I have done any descr_strat modding, so I may be wrong.