The events shown in the forms of the log.nsf are shown in a ‘Computed for Display’ field (EventsR6). This is why the full text search results are not highlighted.
Hack:
add a new field to the forms, set these properties:
Name: EventList
Type: Text / Computed
Value: EventList
Allow multiple values
Display separate values with NewLine
Hide or delete field ‘EventsR6’.