Improving posts quality in Local boards requires, in my opinion, some users from those local boards, who are able to check if this improving is really happening, based on the recommendations proposed by 1miau and Gazetabitcoin.
Good point. After some time, Hatchy could provide insight about all the achievements of the campaign. There might be members doing a good job, learning a lot from that campaign and these improvements should be honored in my opinion. Of course, any local board member is invited to write a summary, if the goals of the campaign are met, as well. 
“plurality should not be posited without necessity.”
Most of the local boards have dedicated moderators who evaluate published posts and delete those ones that have the vicious style and/or dull/irrelevant content.
For instance, Russian board has two high-skilled mods who perfectly cope with their duties including that ones which are relevant to improving posting quality .