Yes, a silly typo on my part. Their documentation is very clear about the use of spaces. Since spaces are used as the separator for search terms, they should not be inserted arbitrarily.
The [] should not be a problem since, according to their documentation, the Episode and Season fields are strings. In JRiver's query language, you can use either [square brackets] or "double quotations" to surround a complete string that you want to search for. A one-word or one-character string doesn't require it, but it shouldn't be a problem either.