You do know that buying land requires documents and stuff right? And that it's not something you can easily tax evade? As if you're only buying buckets of soil lmao.
Of course, the seller has the documents and this sale and purchase transaction is not as complicated as you think. I can still buy land using gold as a means of payment, exchange it for a car or barter for goods equivalent to the value of the land sold. So because I own the bitcoin and the seller accepts the bitcoin then the deal happens. I already have all the necessary documents, so this transaction has been completed.
One problem that could arise from your transaction is that if the seller would go to court and claim you did not pay him for his pice of land you would have a very hard time to proof that you payed him. Even if you could proof it, you would also proof that you would have done something that is illegal in your country also. Still I appreciate that you used bitcoin for its intended purpose, but try to use bitcoin according to your local laws to avoid trouble.