The quote marks on that page are a real mess. Best practice is to use double curly quotes or single curly quotes—not backtick and apostrophe.
See https://www.cl.cam.ac.uk/~mgk25/ucs/quotes.html ("Summary: Please do not use the ASCII grave accent (0x60) as a left quotation mark together with the ASCII apostrophe (0x27) as the corresponding right quotation mark (as in `quote').")
Also, Founder's Caslon is commercially available, at least, it is now. https://www.myfonts.com/collections/founders-caslon-font-itc