*sigh* It’s not about the accent!
It’s GRAMMAR. Take a linguistics class - you’ll be shocked how many basic requirements there are for human speech.
Southerners EVERYONE knows about - they have a few grammar hitches but they are common to everyone, common “errors”. (That still would not be permitted in writing or on newscasts.)
In New England, no special grammar errors. Neither in New York. I’m not as “traveled” (residence) as you but I’ve been around a bit, know many people from many areas, and nope, nothing matches the PA thing.
Basically no-one knows about it, either - even me, living next to them and with western MDers who “should” have about the same patterns. It’s not shown on TV shows or anything. It’s not “advertised”. But EVERYONE knows about New England and NY and the “South” - and many know about Minn/Wisc. Most of these again, are about accent, and not rearranging words or omissions.
Sorry, but grammar varies to, if you think otherwise you are indeed living your biases. The implied or mis-conjugated “be” is nothing new, and as much as you may believe otherwise, its not just something that happens in PA, it may be where you were first or only exposed to it, but its definitely not distinct to PA.
No one would claim is perfect English, but it is NOT something I have not seen or heard far afield from PA.