I’ve found that a couple of Salus ones are rubbish at controlling room temperature. They turn off too late (after the room is warm) and don’t turn on enough when the room is heating from cold. Not sure if it’s way too much hysteresis or too wide a proportional band. Or maybe it’s just all mechanical TRVs are intrinsically rubbish having experienced Honeywell Evohome (HR92) ones.
The radiators are quite generously sized for the room and can certainly warm it well with manual intervention.