I hear you. "When will you be done with this whole topic, AinurOlorin?" Well. . . when I see how it plays out is the most likely answer. lol. And I would expect nothing less.....................! On the whole, I rather like your second Thorin/Thranduil option. They need something to talk about, other than flinging various insults back and forth (beginning with out Thorin, of course) because the short text scene of a single, silent and unrecognized Dwarf being brought in is abandoned with the screeshot evidence of Thorin festooned with webs along with the Company. So provided they all come in together, Bilbo invisible in the shadows, listening....this would work most excellently well.
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Thorin/Thranduil encounter the heated exchange might including the following accusations and rebuttals:

Thorin: "What explanation do I owe to any Elf, you least of all. You stood by idly when my people were driven from Erebor. You gave us not even the thought of aid when we attempted to reclaim Moria."

Thranduil: "Your hopes were vain, and your venture foolsih. What aid is it you think I could have given against a great dragon like Smaug The Terrible? And as for Moria. . . the attempt to reclaim it was more hopeless than you understand. Long ago your ancestors awoke an unspeakable Terror in that place; the dreadful Demon from which they fled after it slew Durin, the Patriarch of your House. Even amongst the greatest of my kind there are few with any power that would avail against such a foe. It was desperate madness that drove Thror to Moria, but there was never real hope. A king needs wisdom, Thorin Oakenshield. Durin's heir you may be, but an heir without proper sense is not fit to lead, and only a fool would think Erebor or Moria viable for reclaiming."

The Elves would resent the dwarves over the awakening of The Terror. About a third of Lothlorien's Elves, including its prince, fled at the arousing of The Balrog, fearing the Power of Evil that now stirred in Khazad-Dum . And news of it would have reached Thranduil. And one can almost hear him mirroring Elrond's words in Fellowship, but more scornful in the mouth of the Woodland King. "Your foolhardy people, driven by greed, seeking riches, caring nothing for the troubles of others. . . What thought did your forefather Durin or any of his heirs give to the effect their rousing of The Terror in Moria had upon my kin? You speak as a fool when you talk of going up in war, not merely against orcs and trolls, but against a Demon Captain of Morgoth, held over from the ancient world. Not all the armies of Khazad-Dum in the days of its glory availed Durin, and you would rush to share his fate, and have me share it as well. And now I catch you wandering in my wood, headed where? To Erebor? Would you challenge the Dragon with your little band? You would bring ruin on us all, Thorin Oakenshield. In your current frame of mind you are but a danger to yourself and others. . . ." And, detained. ___________________________________________________________________ Very nice tie-in of the history, the current status and the relationship between not only Thranduil and Thorin, but of the Elves and the Balrog. I like the idea of Bilbo hearing it on his own, with no one to clarify, having to make his own judgement about both sides and what they have to say about each other and the Quest. Enhances Bilbo's growth too - no one can tell him what to think he will have to decide without wisdom from, for example, Gandalf. It opens up the door for a heart to heart between the jail bars, as Bilbo is deciding what to do..."Thorin, is that all true?" An actual discussion about something so close to Thorin's heart. And we get to see Bilbo make up his mind.

The idea that Bilbo might hear both sides of the story, and that, not having Gandalf there, he would have to make up his own mind. The more personal feud between Thorin and Thranduil, the larger and more ancient feud between Elves and Dwarves. The problem of the Balrog. Will Bilbo see the truth behind both sides of the story?

Would be really interesting to see things set up like this. I'd love to see Bilbo having to grapple with the morality here. Might explain better his behaviour at the Bo5A, when he ends up making his stand with Thranduil. After all, if PJ keeps that part of the story intact, we're going to need to see a good reason (I hope) for Bilbo's decision to stand with Thranduil then.

I enjoy reading how this could play out. It will make for fun conversations either way.