There appears to be a problem when the charge rate and battery capacity are too low to charge the battery to desired SOC by the end of the off-peak period. The charging continues until the desired SOC is reached even though this may be many hours after the end of the off-peak period. I don't think this is desired behaviour or how battery charge controllers operate (I have no practical experience of any system yet).
You can see the behviour with the default app config with a capacity of 8.5kWh but the max charge rate reduced to 1kW:
