The author offers a pretty good 30 day refund policy if the font doesn't work in your use case: "Triplicate has no demo version, but I do offer a 30-day return option: if the fonts aren’t your style, you can cancel your license for a refund."
As for the customer service experience, the author himself has responded (within the day even) to a couple of emails when I had questions about licensing.
Re:Dev Fonts
by thiagotomei on Friday November 20, 2020 @07:38AM
(#25159851)
They give a 30-day free trial, it seems (last item in the 5-reasons list):
"Triplicate has no demo version, but I do offer a 30-day return option: if the fonts aren’t your style, you can cancel your license for a refund."
Chances are it will look significantly different than the PDF once you load it into your terminal. Each of the three terminal emulators I have installed already render fonts very differently from each other.