If the world of HPMOR is some sort of simulation, as you claim, then this is true and significant; your name exists as a fixed value that can be referenced by a program like the Map.
I think these are two separate issues.
One issue is concerned with the wizards’ concept of names. The wizards who created the Map would seek to imbue it with whatever naming convention felt right to them.
The other issue is concerned with how the HP:MoR universe works, and which resources the Map can tap in order to implement its functionality.
These issues are somewhat related, but they aren’t identical. We could very easily envision a world where names are stored on birth certificates, and yet the wizards still believe that, even if Mr. Harry Potter goes through life calling himself “Mr. Spoo”, his name is still Harry Potter, because that’s what his parents, Mr. and Mrs. Potter, called him. On the other hand, we could envision a world where names are stored in some underlying data structure in the simulation, and yet the wizards believe that what a person calls himself is more important than whatever name parents gave him. Or we could envision some combination of the two.
That said, IMO no wizard would conceive of actually perusing the birth certificate database for anything; nor would he deliberately enchant a map to do anything of the sort. For all we know, wizards and witches don’t even have any birth certificates. It’s pretty likely that, even if they do have birth certificates, they don’t have any centralized databases that store them; we never seen any wizard use one, IIRC, neither in canon nor in MoR.
So, “how does the Map work ?” Well, it works the same way Harry’s Mokeskin Pouch works: by magic.
I think these are two separate issues.
One issue is concerned with the wizards’ concept of names. The wizards who created the Map would seek to imbue it with whatever naming convention felt right to them.
The other issue is concerned with how the HP:MoR universe works, and which resources the Map can tap in order to implement its functionality.
These issues are somewhat related, but they aren’t identical. We could very easily envision a world where names are stored on birth certificates, and yet the wizards still believe that, even if Mr. Harry Potter goes through life calling himself “Mr. Spoo”, his name is still Harry Potter, because that’s what his parents, Mr. and Mrs. Potter, called him. On the other hand, we could envision a world where names are stored in some underlying data structure in the simulation, and yet the wizards believe that what a person calls himself is more important than whatever name parents gave him. Or we could envision some combination of the two.
That said, IMO no wizard would conceive of actually perusing the birth certificate database for anything; nor would he deliberately enchant a map to do anything of the sort. For all we know, wizards and witches don’t even have any birth certificates. It’s pretty likely that, even if they do have birth certificates, they don’t have any centralized databases that store them; we never seen any wizard use one, IIRC, neither in canon nor in MoR.
So, “how does the Map work ?” Well, it works the same way Harry’s Mokeskin Pouch works: by magic.