CAcert is based on the "Identity" model to create the Web of Trust (WoT). This differs from the "Financial" model used by other certificate authorities (CA). In the "Identity" model, to establish identity, of all the pieces of personal information that identify you, your name and your date of birth are the most likely not to change, the least intrusive, and therefore is the minimum amount of information CAcert uses to be able to affirm your "Identity".
So having your account reflect your correct name is required to receive Assurance points to gain access to CAcert’s higher level features. See CAcert Point System
It is easy to make a mistake in the form, and you may change your name as long as you are not yet assured. If you have already been assured, contact CAcert Support <firstname.lastname@example.org> requesting to change your name. Depending on the conditions, Support revokes the wrong assurances, you change your data and ask the assurers to enter the assurances anew, or Support asks two assurers for the true data they found on your ID documents and have written to their CAP forms and then changes your account data.