Come on be realitsic, your shitty implementation of "pathing" tiles doesn't work at all. Considering the dawn of custom items, I really think it's about time you add scripting. I think (probably your own implementation of) Scratch would be ideal for this. It's very simple to learn (even children use it), would work great on touch-devices, goes with the philosphy of everything being physical blocks, and would be extremely easy for you to control how programs are written so nothing malicious could be written. I believe this is pretty much the only course of action that can be taken without simply adding more dysfunctional tiles that work differently depending on your browser, ISP, location, and history of sexual activity.

My personal idea is the player can write a script by making a "script room", which works like a normal level. Everyone in a script room is in god mode (can't die, can fly). In here, the owner (or people the owner allows) can use bits/blocks specifically designed for your language. Bits can give or recieve a boolean signal, as well as interact with the world and the entity it's supposed to control. You could have a "turn left/right" bit, a "look in front of self" bit, a "change sprite" bit, a conditional bit, etc., and of course a "start" bit to get it running. After the script has been completed, the player can make a custom item as usual, only they could have the option of applying a script to it from one of their script rooms.

This is just how I'd see it, not sure what you would think of personally, or if anyone else has ideas. Please consider this.