I just found a player base that exceeded the founation limit set by this plugin. They did it by having 2 different players build. Apparently the limits only apply per player, not by TC as I had assumed, so if you have a foundation limit of 50 and 8 players are authed on the TC, you could have 400 foundations. It should be based on TC or am I wrong?

Yup that's how it works.

No. It doesn't work that way. https://umod.org/plugins/building-restriction can limit foundations / height etc.

Or https://chaoscode.io/resources/buildingrestrictor.86/ or https://codefling.com/plugins/limit-entities

THIS plugin limits only by player, not by TC, as some players will have a base with multiple TCs, and I can't be arsed to recode the whole thing to make it work by TC. It works the way it works, and if it stops working that way due to an update, I fix it and no more.