there would need to be a reliable way to identify the cases where any of the 150 processes fail

A 'job started' message could be sent by a wrapper which cares about the process and reports its exit status.

the entries submitted to a central syslog server will tend to be interleaved

syslog is configurable, and one could send the the log messages to different files based on level/facility and host. Anyways, the log line is marked with the host sending the log message, so sorting things out is as easy as grepping the log file for a host.

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}