Thanks! Is there any references for your comment? Why the family being topologically trivial imply that we could correspond the $T-$fixed points? In the example in my question, a copy of $\mathbb{P}^1$ degenerates to two copies of $\mathbb{P}^1$ glued at a point.

Thanks! I know $Fl$ is topologically trivial, but I am not sure how to make use of that at the moment. As for your comment, what is $K$? Is $T$ the maximal torus in $G$?

Thanks! Are you referring to this paper of Kleiman 'The Transversality of a General Translate', or another paper? How does this paper immediately imply that Richardson varieties are nice and have dimension $l(w_1) - l(w_2)$?