Some of these I have done absolutely no research into and may already exist.
Rating Labels
Finish my work on this. This includes getting the data into Kodi and displaying it there.
Permanent EPG Grabbing
The DVB EIT contains a version number. Having an ultra-low priority subscription constantly tuning to each mux and then saving the EIT version number will allow detection of EPG changes that can initiate a full-scale EPG grab.
EPG Now/Next processing
As well as the bulk EPG, DVB also carries 2 single-entry EPGs carrying the current and next event only. Keep track of these for currently recording muxes and look for changes that may require extending current recordings.
Saving EPG metadata with recordings
TVH does save some EPG data with recordings. However, I'm not sure that it updates the title, subtitle and description if they have changed since the recording was scheduled. More research required.
Keeping track of the EPG history for a recording
This is mostly for timer recording blocks. These don't traditionally have EPG data saved. Simply keep track of all EPG events that occur during the recording and save them somewhere.
Recording conflict prediction
TVH will allow more simultaneous recordings to be scheduled than there are available muxes. This is resolved at recording time using a series of priorities to determine which recordings succeed and which fail.
I have built a predictive model in Python using the JSON API that will simulate a portfolio of current and scheduled recordings plus any recordings that will arise from timers in a given period. The portfolio of recordings is executed against a set of modelled tuner hardware and conflicts are identified.