If you inherited it (at least in the US) there will be probate records. And property transfer records. There's LOTS of documentation for that sort of thing.
Records that you inherited it are not enough. Where are the records that your parents acquired it properly? Where are the records that prove the money they used to acquire the house were acquired properly? This is the trouble with a presumption of guilt, proving these things are basically impossible.
No. Probate records that you inherited it are enough to get property transferred to your name and the title recorded as such. If you want to be covered just in case your parents somehow stole the land and falsified their ownership, title insurance is a thing.
None of this is impossible. None of this is unknowable. This all happens everyday.
The problem (this time) isn't that they try to deny your title to the property, it's that you sell the property and they freeze your account with the money in it and now the burden is on you to prove that your parents acquired it lawfully, which you have no way to do because it happened many years ago and your parents have passed away.
No. If you have title, it's presumed that the land has been lawfully transferred. If someone/.gov wants to claim otherwise, they need to prove that. The entire mortgage market is predicated on that. Can someone cite an instance where someone who "inherited property had to prove their parents acquired it legally because their funds were frozen after a sale" because I'd be very interested in seeing that. I'd be a LOT more willing to believe that a sale fell through because the BUYERS couldn't verify the parent's title, but that's not what's described here.
It's not the title which is the issue. You transferred the title and received the money and then the bank took the money. The buyer still has the title and doesn't care about you anymore, and you have no claim to get it back because they actually paid you. But then the bank stole the money they paid you because you couldn't prove how you got the title to begin with.