First, this program is no longer called iCal. I understand the change, but others may be confused.
Second, when searching for all events with a certain word, it is clear that not all events are being returned.
I'm using Calendar under OS-X 10.9.2 and the calendars are iCloud based.
There seems to be no logic to the events that ought to be caught by the search but that are omitted. I'm estimating only about a third of events matching my search criteria (just a word, like "Volunteer") are being returned. I can see all the events with that word in the calendar but they don't all turn up in a search.
I tried re-indexing with mdimport to no avail. This makes Calendar nearly useless, if search is not reliable.