Config CraftPlayer{name=RisenAngel}?

When you try to print a Player, the method: toString() is called. And for the player the toString() return

Code (Text):

CraftPlayer{name=RisenAngel}

So if you want the name of the player you have to do like this:

Code (Text):

player.getName(); or player.getDisplayName();

 

That looks like the result of toString(), which is called when you try to save an object as a string.

Use the player's UUID instead.

 

You can't add anything but Strings, numeric values and ConfigurationSerializables (and maybe one or two things I don't have in mind at the moment) to a config. You have to get other objects like players by one of these things. So, you can't add a UUID to your config, neither. Fortunately, a UUID can easily be fetched from a String.
String string = player.getUniqueId().toString();
UUID uuid = UUID.fromString(string);

 

You don't need to change anything.. it's just a "mistake" here:

Code (Text):

if (cmd.getName().equalsIgnoreCase("reset")) {
            target = Bukkit.getServer().getPlayer(args[0]);
           
            if (target == null) {
                sender.sendMessage(ChatColor.RED + "Cannot find player '" + args[0] + "'.");
                return true;
            }
           
            if(args.length == 1){
                blocksTraveled.put(target.getName(), 0); // HERE HERE HERE
                p.sendMessage("Reseted.");
                target.sendMessage("Your stats have been reseted.");
            }
}

 

Both x)

 

Remove and replace the config file? Probably that

Code (Text):

getConfig().set(p.getName() +".traveled", blocksTraveled.get(p));

Your have an HashMap<String, Integer>. So to get an element you need to set a string as parameter. blockTraveled.get(p.getName())

 

Why are casting an Integer to a Double?