Much appreciated! I finally got it working with some playing around. Then it was just a matter of understanding the CMN_SEC_USERS table as well as the CMN_SCH_JOB_RUN_PARAMS table. Luckily I only have one parameter for this report so I didn't find it difficult to differentiate between the different params attached to the report.
Final query (in case anyone is interested - and note that this is only looking for one parameter on one report, but I'm sure you could adjust it to look for specific parameters depending on the report if looking for multiple reports):
SELECT CMN_SCH_JOBS.NAME REPORT,
Count(CMN_SCH_JOB_RUNS.USER_ID) AS TIMES_RUN,
Concat(Concat(CMN_SEC_USERS.LAST_NAME, ', '), CMN_SEC_USERS.FIRST_NAME) RUNNER,
Concat(Concat(INV_INVESTMENTS.CODE, ' - '), INV_INVESTMENTS.NAME) PROJECT_REPORTED
FROM CMN_SCH_JOB_RUNS,
CMN_SEC_USERS,
CMN_SCH_JOBS,
CMN_SCH_JOB_DEFINITIONS,
CMN_SCH_JOB_RUN_PARAMS,
INV_INVESTMENTS
WHERE CMN_SCH_JOB_RUNS.JOB_ID = CMN_SCH_JOBS.ID
AND CMN_SCH_JOBS.JOB_DEFINITION_ID = CMN_SCH_JOB_DEFINITIONS.ID
AND CMN_SCH_JOB_DEFINITIONS.JOB_TYPE = 50316
AND CMN_SCH_JOB_RUNS.USER_ID = CMN_SEC_USERS.ID
AND CMN_SCH_JOB_RUN_PARAMS.JOB_RUN_ID = CMN_SCH_JOB_RUNS.ID
AND CMN_SCH_JOB_RUN_PARAMS.ATTRIBUTE_ID = 5116015
AND CMN_SCH_JOB_RUN_PARAMS."VALUE" = INV_INVESTMENTS.ID
AND Trunc(CMN_SCH_JOB_RUNS.START_DATE, 'MM') = Trunc(SYSDATE, 'MM')
GROUP BY Concat(Concat(CMN_SEC_USERS.LAST_NAME, ', '), CMN_SEC_USERS.FIRST_NAME), Concat(Concat(INV_INVESTMENTS.CODE, ' - '), INV_INVESTMENTS.NAME), CMN_SCH_JOBS.NAME