That's only kind-of correct... the state was changed, but a trigger focused on the attribute event_type wouldn't fire, because that attribute didn't change.
Instead, use a state-focused State trigger for the event entity, so that the state change fires the trigger. Then add a condition to filter for the press type:
triggers:
- trigger: state
entity_id: event.home_assistant_voice_[...]_button_press
not_to: unavailable
conditions:
- condition: template
value_template: "{{ trigger.to_state.attributes.event_type == 'long_press'}}"
FYI
It looks like "purpose-specific" triggers should be moving from Labs to Core in next month's release (2026.7)... which will include the event.received trigger that handles this issue on it's own, no need for the trigger-condition combination:
trigger: event.received
target:
entity_id: event.home_assistant_voice_[...]_button_press
options:
event_type:
- long_press