According to smoothieware it is supposed to reset the board if you type "reset" as a gcode command
but simplify just say "command received" and nothing happens.
That sounds like an issue with the firmware. There isn't much else to do in S3D than to type "reset" into the communication window and press Send. After that it's up to the firmware to choose how to handle the command.
Well that's not true at all. I just ran some tests and S3D absolutely DOES send the "reset" command correctly. The software is going to send whatever command you type in, but it's up to the firmware to determine how to handle it. So the software is definitely sending the command to the printer, I can confirm that much. There is no reason to say that it doesn't support unknown commands - it will send whatever you type regardless of if it "knows" the command.