I would suggest using the fork real_names_redo it has a far better setup and supports more name systems.
*** Sam joined the game.
Sam has joined the game for the first time, under the name of 'Jayce Carpenter'
Sam has joined the game for the first time, under the name of 'Samantha Collins'
There is a total of 454,000 possible names.
227000 possible boy names and 227000 possible girl names.
View the Minetest forum post here here
/change | Shows the real_name gender choice formspec to yourself
/change [player] | Shows the real_name gender choice formspec to the chosen player
/change [player] [First name] [Last name] | Changes the chosen players name
All of the above require the 'change_name' priv