Using Pythagoras' Theorem to Check Point Distance
There are several reasons why the code does not work.


Here's the body of the first loop for generating points, in pseudo-code:

Pick a random point (x, y)
for t in tileSet:
    Compute distance between (x, y) and t
    while distance is wrong:
        Pick another random point (x, y)
        Recompute distance between (x, y) and t


The problem here is that when you pick another random point (x, y), you only test it to see if it has the wrong distance from the particular point t. But if (x, y) has the wrong distance from one of the previous points in tileSet, you'll never find out because that will never be tested.
The second loop has the same problem. Again, in pseudo-code:

for t1 in tileSet:
    for t2 in tileSet:
        Compute distance between t1 and t2
        while distance is wrong:
            Pick another random point t1
            Recompute distance between t1 and t2


The new random point t1 might be the wrong distance from one of the previous points in tileSet, but that will never be tested.
Additionally, after picking the new random point t1, the code doesn't update tileSet to replace the old point with the new one.