Cheers Erik for your insights!
In this case, there were no worries whatsoever on the RAM usage, however this seemed to be the driver of the box soft-bricking, with enigma2 using up to 1003m of RAM. A swapfile was added to support the eventual large usage of epg and picons, however even with 2GB on a fast usb drive, this was ultimately always making the device unusable and not even booting after a shutdown or reboot (black screen), solved with the workaround above.
After a lot of troubleshooting and testing, following the precious advice, a lot of improvement is experienced as for example enigma2 is now at 366m, thanks to the removal of CrossEPG jobs and the use of EPGImport, instead, still together with EPGRefresh. If this turns out to be the culprit and the usage stays under control, great! We'll know after a bit more testing, as there is only a 10 hrs uptime now and only a single cycle of EPGImport and EPGRefresh. If that was not the cause, there is still some unexpected memory usage growing until bricking the device to identify and troubleshoot