Have we just given up entirely on the idea of calling it "gildar"? Because I'm fine with that if we have.
On higher difficulty levels, the AI gets tons of free gold, so with a 30 gold cost, the AI players can just spam Pioneers without a care. With so many Pioneers, it makes it easy for the AI to just send them out randomly and hope for the best, like ants, rather than putting any thought into what it's going to do with them.
With that in mind, while we could make a mod to change the Pioneers back to a Population cost, and make a separate unit that can create Outposts, the AI might not understand what's going on, and either not make any Outposts (if that ability is removed from Pioneers), or it'll just continue to use the Pioneers to make its outposts at increased cost to itself over the cost to us. I'm not sure if this can be controlled from the XML.
Changing it so there's a 30 population cost on the Settle action would probably work for the AI, so it could still spam Pioneers to its digital-heart's content, but still pay up in population when settling, and you could also solve the issue of over-costed Outposts by making the Outpost action have a different cost, maybe 30 gold, or 10 population, or something. I'm not sure if this can be changed in the XML for a mod, either.