Aha yes ok. It's not meant to be postcolonialism in the sense decolonization of empire in an active military/revolutionary way (rebellion) since that doesn't really make sense to adopt from the perspective of the ruler (and from the perspective of the ruled--or their allies--this would be more like the Freedom tenet)the effects of the Postcolonialism tenet doesn't make much sense
Instead it's meant to be postcolonialism in sense of shifting domestic policy with respect to conquered-now-integrated peoples as a result of the various postmodern developments. (Both those that have happened IRL and also those that maybe haven't been widespread, yet) So the mainstreaming of anti-racist sentiment, racial/geographical equality through reform and reparations, aid and investment/join partnership, etc.
So the on Courthouses is meant to stand for reparations. The trade routes stand for increased (non-exploitative) commerce and the lowering of tariffs/(post)imperial mercantilist policies/preference.
The trade routes is the more hand-wavy effect, but it's important for the gameplay synergy of the tenets.
If you think there's a better term to describe this I'm completely open to renaming it.
I like your idea of a combat bonus near puppet/occupied Cities! I don't think we have that at the moment in the database but we can think about adding it. As a tenet it is quite close to the Patriotic War effect, but there may be more general use on a Wonder, Unique Unit, or just an earlier Policy tree (Progress?!)