I think there is a big difference between using dialect in casual speech and writing and in more formal writing Absolutely!
I'm going to push back a bit about "borrow" and "lend", partly because I'm currently learning a language where the word for both is the same and it reminded me of a conversation I had once with a Geordie and someone from Northumbria (I know it sounds like a particularly bad joke, but bear with me!).
The Geordie reminded me that I had said he could lend my book - I was confused. I thought he wanted to borrow it, I already had the book in question. The other person looked at me and didn't understand my confusion at all - he knew exactly what was meant, took the book out of my hand and gave it to the Geordie.
I tend to think that if a linguistic quirk is well-known, used and understood by people from roughly the same geographical area it is more than just a common error (though obviously ideally users of said quirk would know that it is a deviation from standard English)