Issues With the Place Name Authority
First, users should recognize that the PNA within FTM is an aid to try to standardize place names, make them complete names where possible; and serve as a spell checker and county finder.
There is no Genealogy Commandment that the user use the suggested name from the PNA. This is certainly true with historical place names.
That said, there are a number of problems with the PNA.
1) Strict use of a four unit place name at the longest level. It should be at least five units, or even six, or even unlimited. Boroughs & hamlets don't properly show the towns that they are located in. Neighborhood names of larger cities (or even medium-sized ones) are not shown - or, if they are, omit the city or county. For example:
Venice, Los Angeles, California, USA (in PNA) should be:
Venice, Los Angeles, Los Angeles, California, USA
Marina del Rey, Los Angeles, California, USA (in PNA) is ok
Because Venice is a neighborhood name (an old annexed city) within the City of LA, which is in the County of LA; but Marina del Rey is an unincorporated place within the County of LA.
2) The PNA does not gather together common names within a state to help serve as a county finder very well. For example, if one enters the town of Washington, Kansas; one is given a list of apparently all the Washingtons in the United States - but the various ones for Kansas are not grouped together. I still have to make use of a county finder at various spots on the internet. Here is the listing of the 14 townships in Kansas called Washington in Wikipedia (their disambiguation pages are good for this purpose):http://en.wikipedia.org/wiki/Washington_Township,_Kansas
And, even that list doesn't go far enough because there is also a city named Washington in Kansas.
3) There are a number of localities in the US where the PNA has wrongly added the word "City" to the end of the name. I can't think of a specific example right now, but have run across several in recent months.
4) Various misspellings
5) Comprehensive problems with German Place names as reported above.
cc to FTM Bug Report
So, in the meantime, you can sometimes still get the place name resolved for purposes of including in the heirarchical name view by using the new feature to place the parts of the place name starting from the left out of the part of the name being resolved.
However, because of the problems with historical names, which I can't resolve with the PNA because it uses current names, the heirarchical view is not of much use to me and I don't use it.
Other than using resolved names for the heirarchical view, one can simply leave the names unresolved, and not have any impact on anything.