Andor's Trail

So I've gotten across the bridge, ludicrously overleveled since I didn't know that area was even accessible (2015 AT still in my head) and found the Roses quest.

Seemed easy, though siding with Unrokh apparently gave you Andor's Bonemeal Box. Does it do anything special? Do I need it or something? I chose not to take it since Unrokh is kind of an arse, but I'm just curious.

Is there still a plan to get a use for this in the future?
Siding with Unrokh seems to be the "bad" ending of this quest, even though you get rewarded all the same. But I've read that Hannah's rose is just a suvenir, while this may be useful at some point, so maybe it worths to side with "evil" here?

There's no plan for it yet. But who knows if and what will have consequences in the end

Is it possible that you can encounter Unrokh again and loot the bonemeal box?

No, don't expect this. You got a memorial east of the castle instead. Life is full of choices...

Don't sell any unique item! Even if we have no plans for it, that could change (although typically we make sure you can't sell such a thing!). If you discard it, do so where you can find it again if you need it.