Default Alias Standard

What is the standard for the default alias script? There is inconsistency.

Currently, I have been using the script and name the author would indigenously write their name e.g. Plato’s name labelled as Πλάτων. Then, for the sort artist, I use the name written in Latin (this is, I believe, so that things across many different scripts will sort nicely). This is how it is done at Musicbrainz.