Running 0.17.79 w/ mod 0.17.2.
When I do a '/teleport_to 0 0' it dumps out:
237.833 Error MainLoop.cpp:1195: Exception at tick 6384155: Error while running command "teleport_to": Unknown entity name: player
stack traceback:
console-extended/Commands.lua:577: in function 'makeValidTeleportLocation'
console-extended/Commands.lua:340: in function '?'
console-extended/Commands.lua:493: in function <console-extended/Commands.lua:482>
stack traceback:
[C]: in function 'can_place_entity'
console-extended/Commands.lua:577: in function 'makeValidTeleportLocation'
console-extended/Commands.lua:340: in function '?'
console-extended/Commands.lua:493: in function <console-extended/Commands.lua:482>
237.833 Error ServerMultiplayerManager.cpp:92: MultiplayerManager failed: "Error while running command "teleport_to": Unknown entity name: player
stack traceback:
console-extended/Commands.lua:577: in function 'makeValidTeleportLocation'
console-extended/Commands.lua:340: in function '?'
console-extended/Commands.lua:493: in function <console-extended/Commands.lua:482>
stack traceback:
[C]: in function 'can_place_entity'
console-extended/Commands.lua:577: in function 'makeValidTeleportLocation'
console-extended/Commands.lua:340: in function '?'
console-extended/Commands.lua:493: in function <console-extended/Commands.lua:482>"
237.833 Info ServerMultiplayerManager.cpp:776: updateTick(6384155) changing state from(InGame) to(Failed)

Have tried it w/ mutlple X Y coords, and still crashes. Used 0 0, 1 1, 1.1 1.1, -1.1 -1.1, and each time causes a crash.
Tried 'x,y' and it just displays 'teleport to requires w arguments: x and y. Example usage '/teleport_to 0 0'

That is probably an issue with the internal name change made by the devs. The player character used to be called 'player' and is now called 'character'. I will look into this soon.