This is not an answer to your question; it is just a clarification of terms. If one person signs the note, that person is called a maker. If more than one signs the note, then each signer is called a co-maker. If any co-maker does not benefit from the loan, then they are known as an accommodation party, and the one getting the loan proceeds is called the accommodated party.
A guarantor of payment or performance is also, in most cases, an accommodation party.
What Reg AA defines as co-signer is just a co-maker or guarnator who is an accommodation party in a consumer loan.