This is only tangentially related, but is the combining grave accent (as a jenkim) supposed to be placed before or after the target character? I've found that some fonts (Noto Sans Coptic) want it before, while others (Segoe UI Historic) want it aft…
You could copy the text from Tasbeha.org, then put it through the Coptic font converter from copticchurch.net at https://www.copticchurch.net/coptic_language/fonts/convert. Tasbeha.org uses Coptic Standard, so you should pick CS Avva Shenouda as the…