Interestingly, all but one of the town names you mentioned are outside Allegheny County. If these names were a 19th-century attempt at branding, the PR geniuses closest to home never really got into the swing of it. (Although in fairness, whose heart is so cold and drear as to not leap for joy at the sound of "Wilmerding"?)
But names, like branding efforts, can be misleading, or even outright deceptive. Unity Township, for example, wouldn't exist today if it weren't for disunity. By the late 1780s, residents of the Westmoreland County community wanted to separate from Mount Pleasant Township; according to the 1906 History of Westmoreland County, they did so because the offices of their local government were too far away. Moreover, it shared its name with the Unity Presbyterian Church, and we all know how rife with internecine conflict the Presbyterians are. Put all those folks in a synod together and watch the fur fly.
Or take Economy, an early Beaver County settlement that many nearby residents probably think had something to do with paying homage to free enterprise. The name was chosen by German immigrants who were members of the Harmony Society, which if you think of it had a somewhat Orwellian name of its own. According to the Pennsylvania Historical and Museum Commission, which maintains the old Harmonist settlement, the German settlers named their town Ã–konomie, a German word that translates as "economy" -- but not in the way you usually think of it. The Harmonists used the word in the sense of being "economical." Theirs was a simple, largely unadorned lifestyle, though they turned out to be pretty shrewd businesspeople as well: If you've visited what is now called "Old Economy," you know the Harmonists ran textile shops, blacksmith's forges and even printing presses. Once the Harmonists began to die off -- their faith frowned on reproduction, which put a crimp in new membership -- their settlement began to shrink. And the town they settled in became known as Ambridge. This name actually was given to it by Pittsburgh industrialists, though that doesn't say much for their wit. "Ambridge" was merely a shortened form for "American Bridge," one of U.S. Steel's subsidiaries. (Am-Bridge, get it? So much for wry irony on the part of Carnegie and Frick.)
"Liberty" is a more complicated case. As you've no doubt noticed, Pittsburgh has both an East and West Liberty, and Allegheny County also boasts a Liberty Township. But you've probably also noticed that no one in the county seems much freer as a result. What gives?
Originally, "liberties" were undeveloped areas on the outskirts of town. Since nobody really owned or used them, anybody could turn their cattle loose for grazing. (Imagine an 18th-century Point State Park, except with a slightly smaller chance of stepping in something nasty when you aren't looking.) Eventually, though, the thieving capitalists came along, as they always do. The land was surveyed and sold off, and places like East Liberty became home to numerous mansions. But perhaps those early residents had a sense of irony after all: In homage to the area's history, the new neighborhoods kept their old names, a reminder of days before the mansions, when you actually were at liberty to walk wherever you wanted. This early example of suburban sprawl helped set a precedent for many suburban developments that followed: You name the community after what you destroyed to make way for it -- hence Rosslyn Farms or Bradford Woods.
As for Freedom, Pennsylvania, I'm sorry, but there's no way around it. That place really is an Orwellian tyranny.