> That title search was done in government records, tracing back to the original grantor, the government, which keeps the records.
Who happens to be the entity keeping the registry of the land titles, has little relevance on ownership, as long as it was a trusted record keeping place. Most of the time land title's are registered at town halls, local places where people went to register local homesteaded or purchased land (not be granted land).
But, I think that you are confused. In the US, most land was likely homesteaded, not granted. Some of it was homesteaded before the government laid claim to it, some of it before the gov. existed. Either way most of it was not owned by any government to "grant". A grant is a gift, and was sometimes done, such as when the R&R companies were granted land for building the cross continental rail. But this is the exception not the rule. Either way, the land would no longer be owned by the gov. and likely any previous ownership of it would be hard to backup. Land which cannot be traced to a legitimate owner (even after theft) falls under the same terms as abandoned land and can naturally be re-homesteaded legitimately.
> That you're living on stolen land, and you were aware it was stolen when you purchased it.
When the record of ownership dies, so does the claim. Unless another record can be proven beyond it, at which point the land will gladly be given to them, that is after all why I paid for title insurance. But, baring that point, that last known owner was the most legitimate owner (not the gov.). And since then, it certainly has been sold many times. And none of those sales magically give the gov. ownership of it. I am not claiming that this stuff is clear after 100+years, but there is a fairly good chance that I am currently the most legitimately known owner of this land.
So, to claim that "I am living on stolen land" is disingenuous. I am living on land that was "likely once stolen, but that has since then likely been legitimately acquired". Those are two very different statements.
All this said, there is no evidence that this land should even remotely be considered owned by the U.S. gov.
> That you're claiming title granted by the organization you name as the thief.
Again, it was likely not granted to the last traceable owner, it was likely simply registered to that owner in a related organization's records. There is a big difference.