Home automation scene limited to turn off after maximum 4 hours. Is there a workaround to make this a specific time?

You should be able to use multiple automations, each of which sets a scene with no later on or off time. I have one that sets a particular scene at sunset (wish I could do sunset - 30 mins for example because I don't think it happens early enough), another that changes the colours later in the evening at a fixed time (but not if I'm home, and again I agree that adding some randomness to this would be nice) and finally one that turns the lights off later on if I haven't come home, but which roughly corresponds to the time I would turn them off if I were.

tt2

You're welcome. In lieu of the ability to add some randomness to the off time you can again create more than one of these and assign them to different days of the week, e.g. leave the lights on longer on say Friday & Saturday nights.

tt2