The English word Samaritan comes from the region of Samaria, which is how outsiders have named the community since antiquity. The community does not name itself that way. Its own term for itself is built on a root meaning to keep or to guard, and it understands the name as the keepers, meaning those who keep the Torah. The first letter of that name is this one.
The difference between the two names is not a matter of translation. One locates a people by where they live and the other by what they do, and the second is a claim: it says the community is defined by its custody of the Law given to Israel, and that it has kept it. The community regards itself as Israelite, descended from the northern tribes, and its account of the split with Judaism turns on which mountain God chose and on which community remained with the original practice. The Jewish account of the same events is different. Both are old, both are internally coherent, and neither is going to be settled by the other.
An atlas has to make a choice about which name to use, and the honest choice is to use the received English name, because that is what a reader will search for, while recording the community name and what it means. Naming a living people the way they name themselves is not a courtesy. It is a piece of information about who they take themselves to be, and it belongs in the record beside the label everyone else uses.