You could say that about any of the Boosts that deal with improvements (e.g. Farm a resource, Build a quarry, Build a pasture, Improve 2 sea resources, etc.). At most I think you could claim that the Boost descriptions lack specificity in regards to tile ownership, but honestly it's splitting hairs at that point and not something I'd consider a bug. Not to mention, and I don't think I'm exaggerating, most players are already aware that the trigger for these Boosts require the player have tile ownership (i.e. their territory). The verbiage & mechanic has been the same since the initial game release in 2016 so at this point it's wishful thinking that FXS would go back and alter the text.