The examples you give are all administrative functions, yes.  Another one is 'Lieutenacy Areas' (see https://en.wikipedia.org/wiki/Lieutenancy_area) - the current Lord Lieutenant of Fermanagh is Alan Brooke, the 3rd Viscount of Brookeborough (see https://en.wikipedia.org/wiki/Alan_Brooke,_3rd_Viscount_Brookeborough) which I'm sure is an extremely important job and King Charles III simply couldn't manage without him, although what he actually does all day escapes me for the minute :) 

However County Fermanagh is not involved as an administrative unit in a lot of rather more mundane administrative functions such as: 
- emptying bins
- running public libraries 
- running the NHS
- paying your rates 
- running fire brigades
- fixing the roads
- blah blah blah
(Such matters are attended to by district councils or fancy fellows in Stormont). 

On the balance of consideration, about 95% of civil and municial administration does NOT use County Fermanagh.  
Hence the 'historic' add seems fine to me, as a general rule of thumb. 