There is m-TVGuide, it's an EPG addon for Kodi that works much better than Simple IPTV PVR addon.
Is it perhaps possible to look at it and see if you can integrate some of your code into it or add some of it's features into your addon? It also supports logins for several EU streaming services, so it might be possible to modify it to pull EPG data correctly and also start playback. https://github.com/Mariusz89B/script.mtvguide
Then there is also TiviMate
It has a very nice feature to see a transparent playlist with epg data while a stream is playing if you press left, scrollable from top to bottom without exiting a stream first.
Hope such a feature can also make it into your addon.
With TiviMate you can watch live TV channels from your IPTV provider on Android set-top boxes. Main features: • Modern user interface designed for big screens • Support for multiple playlists • Scheduled TV guide update • Favorite channels • Catch-up • Search • and much more IMPORTANT...