It really isn't.
It is though, because it's not as easily dismissed as someone misspeaking. The information comes from multiple sources.
I mean, people misspeak, or speak more casually, all the time. If the word changed, then I would appreciate being filled in rather than just assuming thus.
Sure, but it's also not really necessary. I feel that way about major changes, like say, Discovery Klingons. If they're going to be drastically different, I think some sort of explanation is in order. It's why I actually appreciate something like TMP... the Enterprise looks drastically different than in TOS? They explained why.
When it comes to down to literal semantics? I'm comfortable with context clues and comprehension. They called Titan-A a refit. While it may not have appeared to be a refit from my understanding of the word refit, I can use my general language comprehension skills to understand the context of the word they are using.
People in the UK call crispy fried potatoes "crisps". I call them "chips". This doesn't cause some sort of unintelligible breakdown of communication... even if I had no actual foreknowledge that people in the UK called them crisps, if I heard people speaking, eating the food, and saying the word "crisps"... I would reasonably assume "Oh, they call those crisps, even though I understand them to be chips."
Now granted at the end of the day, was it kind of stupid to call either of these ships a refit? Absolutely. Honestly though I think this was more of a result of some clashing between someone like Matalas and Paramount. While I haven't found any quotes confirming it, Matalas very much seems like the type who have wanted to just use the Luna-Class and have it just be the Titan. But someone at Paramount wanted a newly designed ship, probably well into the process of the script having already been written to include the Titan. So then we end up with a clunky "It's the Titan, but not."