Quickly:
The data you have to work with depends on the source. OTA EIT data is usually the worst, with the least amount of information. Schedules Direct is better. You may find that in the UK OTA MHEG5 data collected using EPG Collector is better data. EPG Collector can also enhance the data by collecting metadata from TheTVDB before supplying it to MC, which is what I do in Australia. There are UK users of EPG Collector who seem to make it work for them just fine.
With my data I have [Media sub Type] = "Movie" and [Genre] = Comedy, Action, Music, Drama, Other, Horror, Romance, Documentary, etc. With a custom view of the EPG data I can sort and find any combination, in Standard View. I could probably create a suitable view for Theatre View as well. In addition I have more information in the [Keywords] tags, which tends to be a bit better. For example all the "Other" type movies actually have a Genre in the Keywords, such as Movie:Crime, Movie:Fantasy, etc. Some of the Action movies get re-categorised into "Adventure" as well. A few of the movies even have a Keyword of HDTV, which is handy.
So if your source has the data, and that is entirely out of JRiver's control, then yes, you could view upcoming programs by the categories you want. But it will need a custom view of the EPG Data I believe.