Text format (regular expression)

Hi first i would thank the developer for this nice plugin its helpful and i want help with add custom option for Text format (regular expression) so i force my fields only to accept Arabic characters and also custom validation text message when the user enter wrong language letters.

I saw another plugin have such feature but its only for username field
without an option to edit the (regular expression) as custom or its validation text message.
https://www.ads-software.com/plugins/wordpress-special-characters-in-usernames/

I hope see in next update the developer add this option so everyone can use it for its favorite language.

thank you