I think there is a clear need for a COMPOSITION archetype that is suitable for patient reported data, made outside of the context of a clinical encounter.
A very simple use case is where the patient has a set of electronic scales recording their weight each night at home, and entering that into a (openEHR) compliant PHR. The weight measurements will obviously be in a OBSERVATION weight archetype. However there needs to be a suitable composition to act as a container for the measurements.
This is a summary of the current top level COMPOSITION archetypes
discharge - for release from hospital
encounter - implies some interaction with health provider
history - persistent store of health data
plan - suitable for plan of care
prescription - medication related
problem_list - persistent store of problems
report - has inbuilt requirements for requesting clinician etc
I do not think any of these are suitable for holding purely patient reported data.