yes as tittle...

when you try and use curly brackets {,}, within a run_command value..
it must pick that up and mess with the parsing of it, as you get an "An unexpected error occurred" when "reload_custom_event"
can JUST remove those curly brackets (thats being used in a give command as part of a NBT section of a potion) and it works ..

silly me, it wasnt the { i used, it was the " within the tag, and i used a / before it, and not a \ ...
all sorted now, false alarm sorry ..