Being able to limit the amount of times a certain modifier can be applied: Quartz, Redstone, Lapis, Reinforcements, etc. (alternatively also the effectiveness of things like Sharp so you can still put the same amount of quartz into it and get 5 levels of Sharp but it only makes it 75% as strong as it would in vanilla TCon)
I read something about the caps being hardcoded in tinkers construct but maybe you can get in touch with their dev team to open up some sort of api for that instead of having to overwrite the existing modifiers
Global Adjustments to specific Tools/Weapons stats (to be able to nerf/buff certain weapon types since as of right now the crossbow is the only relevant weapon on my server)
If it's not possible to do this low level you might be able to automatically add a modifier to each tool type like "Pickaxe Stat Adjustment" that is applied if configured
This ties into both requests: limit/disable certain modifiers for specific tools/weapons.
For example only allow 3 levels of redstone to be applied to cross bows but all 5 for pickaxes or disable beheading for all of the ranged weapons (individually, no need for a "applies to all ranged weapons" category)
Support for PlusTIC katana and lasergun
Option to autofill the config with existing traits