What is “min_lod_value” and “ui_category”?

The TDESC describes what they are in some detail.
ui_category = If enabled then this trait will be displayed in a specific category within the relationship panel if this trait would be displayed within that panel.
Right now we only have personality traits in the relationship panel (least last I remember), and when you search up examples it only ever looks like <V n="ui_category" t="ui_trait_category_tag" /> in the tuning, and only seems to be in personality traits and a few random ones.

min_lod_value = The minimum Sim info LOD necessary for this information to persist on the sim info. e.g. A statistic tuned to FULL will not persist on sims that lower than FULL. LOD order, high to low, is FULL, INTERACTED, BASE, BACKGROUND, MINIMUM.
I know I saw someone discussing this before but can't find it, they had a much better explanation/insight on it. Basically this determines if the trait, statistic, etc. stays on sims when they are...loaded, I think is the way they described it? I believe FULL is probably the currently selected sim, interacted is probably the sims you are interacting with, base is probably nearby, background is probably distant, minimum is probably including ones not even loaded. So for example, on traits that your played sim usually gets while going about their story, stuff like "trait_Hidden_BeenKissed" are FULL. On traits that are spawned on sims/common, like "trait_Breasts_ForceOn", these are set to MINIMUM.