So, in the case of St. Asaph's, as it closed in 2012 its no longer available for newgens to use. Broadly speaking in the working of the game, locations can be marked as "Do not use as place of birth" and so only 45 out of the 137 locations are available. This aspect is currently working as its intended.
On one hand, in the situation of Wales with 137 locations in total making them all available doesn't sound unreasonable, but contrast that with say Italy which has over 10,000 locations in the database it means there are very different situations for different nations.