Oh, it works fine in Japan with their syllabic and logographic writing systems.
We're stuck with the alphabet and didn't get any extra spaces.
Hold up here. Lets not be spreading incorrect information now. The Japanese version only allows three spaces for first and last name, which has been standard for Atlus games for a very long time. The English version of Persona Q was expanded to allow for six spaces each.
Persona 3 and Persona 4 were expanded from three to eight.