You don't even read what you post. Leo XIII in NO WAY condemns the form of government known as democratic republicanism.
Methinks that thou art blissfully ignorant of something called "Americanism" - a heresy, condemned by the very Pope whom you refer to.
Look it up - read about it (probably for the first time). And then enlighten your mind in regard to Americanism and the very famous "McGylnn Controversy" which took place in the Archdiocese of New York around 1890........in which the Rev. Dr. Edward McGlynn was formally excommunicated for publicly espousing tenets of this very heresy.
......and which is why Archbishop Michael Augustine Corrigan of NY never received the Cardinal's red hat.....as his clergy was infected with this heresy!
Oh......I'm sorry........this was not covered in your seminary courses on great "Catholic" teachers like Karl Rahner, Hans Kung, Edward Scheelebex, Teihard DeChardin, etc.