King Naugladur, looking again at the three issues:
We don't have enough information about Finrod's responsibility; all we have is a general comment about what was done by the Noldor. The word 'evicted' was never used to describe what had happened to the Petty-dwarves in Nargothrond. All Mîm said was that his people were the first ones who dug there, but he didn't say what had happened to them. They could have left or died off. As the halls were vacant, he probably has a good claim on them, if not one on Finrod's hoard.
We know that Túrin kept at least one part of his promise, that he would spare the lives of Mîm and his son; but we don't know if he paid the promised compensation in gold. Perhaps he had already done so by the time he was captured,
hence Mîm asking the Orcs that he not be killed.
We don't know from the information available if Túrin paid this promised compensation to Mîm by the time he died. If he had done so, then the debt was paid. Even if it was not, I don't see Húrin having, in the circumstances, any responsibility for his son's unpaid debts. As far as he was concerned, Mîm betrayed his son to a fate worse than death, something of which he had had personal experience.
That's where Maedhros and Maglor messed up so badly.
Tolkien makes it clear that when Elves married, they did for love, or at least freely. Any idea of trying to marry a fellow Elf against (in this case) her will, was one of the worst things any Elf could do. To this is added the political dimension that Lúthien was the daughter of Thingol, the Lord of Beleriand.
I would have thought that Maedhros and Maglor, who appeared to have been reasonable Elves, should have
tried to find out the truth, by asking those in Nargothrond what went on, and then asking their cousin Galadriel to get information from Melian.
Once that was done, those two brothers (and possibly also Amrod and Amras) should have formally apologised to Thingol for the disgusting behaviour of Celegorm and Curufin towards his daughter, and offered to pay compensation,
before bringing up the issue of the Silmaril. While they should have mentioned the Oath, it should have been left to the end, they first mentioning that the jewel was their father's property, which had been stolen by Morgoth, and that their claim still stood, regardless of any oath.
I'm not saying that it would have resolved matters; but I thought that Maedhros and Maglor, and possibly also Amrod and Amras, should have first tried this kind of approach. Certainly the lack of an apology concerning what happened to Lúthien was completely wrong.