Good to hear your setup is working all from one Raspberry Pi!
Unfortunately, I am not the best with timezones however I have pushed an update to help address the timezone issues. There is no longer a choice of timezone during the install and will now default to UTC. So long the server’s time is set correctly, I believe this will work just fine. I did some more testing and the program preview seems to be working well. The logging is now fixed by applying the timezone difference before displaying the time. This is done against the OS timezone setting.
This change will mess up old log entries. The best thing to do if you update would be to empty the two log files defined by $log_file and $log_previous. Also, if you are updating please change your config.php timezone to UTC otherwise the calculations will be off as well. There was no good migration path hence the manual interventions needed. Just to be clear the manual changes are only needed if you are upgrading to the new files and does not affect new installs.
@Vaughano and @djagerif please let me know if this helps address your issues. I am sure more work needs to be done for this issue but need to see where we stand before proceeding. Thanks!