This article explains the limitations of stream mode syslog server configuration.
SRX Devices has a limitation of either 3 or 8 servers which can be configured for stream mode.
root# commit check [edit security log] 'stream' number of elements exceeds limit of 3 //or 8 error: configuration check-out failed: (number of elements exceeds limit)
2021-09-09: Added SRX5400 to High End.