I’ve seen the alternator light flicker many times on these but never stay on after even a tiny blip of the throttle

I like the colour

Do you find the bike needs a battery maintainer permanently, Or can it be left without that, provided the temperature is above say 5 degrees C?

Sorry but the battery light behaviour is not normal. Did you maybe swap the lightbulb to LED, since I see that you did something with the background lights too? The battery light shouldn’t come up at all and if so, it should immediately go away as soon as you rev it a bit over 1000. The check oil indicator has to light up before starting the engine as well, which it doesn’t. I believe you did something with LED replacement bulbs, which would explain this behaviour to me. (Also the clock not being visible)