Property setting elements have also been rejected, see this thread: http://tpt.io/.224643
If you read my post, you'll notice I said "property setting elements", i.e. exactly what you've just suggested, not "command particles which run Lua".
Property setting elements have been rejected even if they don't run Lua.
It really is. If you're really desperate, there's a cmnd script on the script server, and my mod has command signs.
Daungerous. Dongerous. Hmmm....