Spotfire "action logs"  collects information about the user activity. From the action log, we can also know which user has accessed a particular report from library.

All Supported Environments

Execute the following query on Action logging database:
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Select distinct user_name from [dbo].[ACTIONLOG] where [LOG_CATEGORY]= 'library'  AND [LOG_ACTION]='load_content' AND ID2 like '%[Library path of the report]%'
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Here is an example:
Select distinct user_name from [dbo].[ACTIONLOG] where [LOG_CATEGORY]= 'library'  AND [LOG_ACTION]='load_content' AND ID2 like '%/testfolder/testreport%'

Note: The preceding '\' in the path (right before the 'testfolder' in the above example) indicates the root library folder.

Note: The above query was tested on MSSQL Server Spotfire action log database. 

How to list all of the users who has accessed a particular report from Spotfire library?

https://docs.tibco.com/pub/spotfire_server/7.14.0/doc/html/TIB_sfire_server_tsas_admin_help/GUID-EC5DB4C9-1528-43D8-9D1B-E3D0EC39164C.html

https://docs.tibco.com/pub/spotfire_server/7.14.0/doc/html/TIB_sfire_server_tsas_admin_help/GUID-67B1DBFC-B1DB-49B1-A492-4B684FAADB72.html