I had some roof issues as a seller. Not sure if it applies to your area or situation, but I was deciding how to proceed after a leak formed a few days before closing. I remember wanting to ask the buyer for more money if I was to replace the roof, which was old and in poor condition, riddled with patches. Those repairs had lasted several years btw. We knew it was old but hoping it would at least continue to function. It did not. And while I wanted to ask for more for the buyer to contribute to the replacement, since repair was no longer an option at that point. My listing agent explained to me that while an old roof may detract from the value, a new roof would not add value. An interesting distinction, as in my mind, it was the opposite.
Since the buyer did in fact pay over asking, and was very easy to work with through negotiations, I, after careful deliberation, bought the buyer a new roof.
It hurt my bottom line since I wasn't expecting it, but it was the right thing to do and saved the sale. And looking back, that roof while not cheap, was a just drop in the bucket in the big picture. Besides, as an investor, if I don't have enough cushion for things like this to come up and still be in the green, then it was probably too risky a project to begin with. Besides, in the end, I am glad to know that the leak occurred a week before, and not a week after closing. Since I look it this like a business, the buyer is my customer, and I want my customers to receive a quality product - and ultimately they did!
So I'm not sure how much of my experience translates to yours, but these things do happen and flexibility is important. That said, ultimately I went with the roofer's recommendation, which was that that roof was beyond repair and had to be replaced. So if I was in your shoes, I would wait for the roofer's evaluation. Yes, roofs are important and expensive and anxiety inducing, but unless I knew more about roofs that a professional roofer (which even as an inspector, I do not), then I would wait for their professional evaluation. And if I was the buyer, I would at least elect to choose my own roofer for that quote.