How can I change form field errors in Appoinments +

I would like to change my required form field errors in appointments +.

For example if someone does not fill out the: Address field the error says: "Please fill in the requested field". Since there are many fields on my site (some are required some are not) this may lead to confusion as to which field needs filled out.

Is it possible to change these required form field errors to something a little more custom?