I think her backstory should be explained by a spin-off or a caeon comic seperatly from the main series as there will be hardly any time to explain her backstory compltly.

I would agree that Kali should return

She only had one appearance in the series and she should return to give her one another chance to appear before the series end

Please bring her back.

There's still some bad blood between her and El that need resolving

Plus her vision manipulation powers could be useful in the final battle against Vecna (and her using her powers on the others could be hilarious)