Add the recently added "object:property-change:accessible-help-text"
event to the event tree, see at-spi2-core commit [1]:

    commit 93b4247e7a99cba671f0ca8e752073de639e7234
    Author: Michael Weghorn <m.weghorn@posteo.de>
    Date:   Wed Jun 12 11:05:58 2024 +0200

        Notify about HelpText attribute change

This e.g. allows to filter for this event
in Accerciser's event monitor.

[1] https://gitlab.gnome.org/GNOME/at-spi2-core/-/commit/93b4247e7a99cba671f0ca8e752073de639e7234