Thank you for contacting us and your question.
After discussing internally, you could indeed try to implement your own grammar definition to support actuarial notation. This would normally be better that the default "standard" grammar we provide with the iink.
The main concern is that as our technology has not been trained with actuarial data, we cannot commit the accuracy will be satisfying.
Are there any plans to implement actuarial notation into myScript's Interactive Ink SDK math rules?