Just based on how often I notice someone mispronounce a word without realizing it (or have done so myself and realized it later). Statistically I’m probably still doing it with some word.
There’s meant to be a fada over the a (á), so it’s definitely meant to be a longer vowel sound.
Take the name Sean for example. Spelled like that it’s actually pronounced shan, and means old. The name that we all pronounce as Shawn is actually spelled Seán