As someone else said, ordination isn’t a magic bullet for making someone really good at apologetics. Many priests are middling-to-bad at that. For diocesan priests, their main job is not to be an apologetics expert but rather to give the sacraments to the faithful and to be reasonably competent at addressing the basic questions that come up over and over, which would probably be the same questions that come up on this forum over and over (like, if God is all-powerful and loving then why does evil exist in the world, why does he let little children die, how can I know if my dead loved one went to Heaven etc.) Diocesan priests also usually don’t have a lot of time to spend sitting around studying apologetics. I can see priests who are members of orders, or are specifically tasked with studying theology or apologetics, becoming more expert at it, and in fact there are a number of clergy experts.
The good thing about apologists like Scott Hahn or Jimmy Akin is that they have the background and knowledge to respond to Protestant concerns and kind of speak in Protestants’ own language. Most of us cradle Catholics, including many priests, are lacking in understanding of those. My eyes just glaze over when people start arguing about stuff like “justification”.
As for “how do we know their answers are correct”, they’re high-profile enough that if Jimmy Akin really said something wrong, 5 other apologists would jump in and correct him. Similar to what happens on this forum when a regular poster makes some boo-boo. 5 other regular posters will correct him. Crowdsourcing helps things be more correct. You should also be constantly learning and growing yourself so you can better judge for yourself the quality of someone’s answer, whether it’s Jimmy Akin, Cardinal Burke, or Bishop Barron.