How to reproduce:

Create Item: log[/tmp/testlog]
Create Trigger:

(

{localhost:log[/tmp/testlog].regexp(a)}

=0&

{localhost:log[/tmp/testlog].iregexp(b)}

=1&

{localhost:log[/tmp/testlog].regexp(c)}

=1)|(

{localhost:log[/tmp/testlog].regexp(d)}

=1|

{localhost:log[/tmp/testlog].regexp(e)}

=1)|

{localhost:log[/tmp/testlog].regexp(f)}

=1

Then click log trigger wizard icon on item list, the parse error appears as attached screenshot.