If I am understanding what you are trying to do correctly, this should do the trick:
select ccn.name from bpm_run_processes brp, bpm_def_process_versions bdpv, bpm_def_processes bdp, cmn_captions_nls ccn
where brp.id = your_running_process_instance_id
and brp.process_version_id = bdpv.id
and bdpv.process_id = bdp.id
and bdp.id = ccn.pk_id
and ccn.table_name = 'BPM_DEF_PROCESSES'
and ccn.language_code = 'en'
Jeanne