Why would I want to use UIBUILDER?

You need to remember that when you run NR under HA you are actually firing up a docker container - i am pretty sure they do not expose that file system to you as the end user.

You would be better off installing Node Red on a different box/VM and then install the Node Red Webhooks add in that provides the link between NR and HA - you will get all the same functionality out of the box and not be tied into their release schedule or limitations.

Craig