Thawing Glaciers return to hand interaction
Thespian's Stage will return to your hand.

It doesn't matter that it became a copy of a different land. The effect "Return Thawing Glaciers to its owner's hand at the beginning of the next cleanup step." is still around. The "Thawing Glaciers" wording in that text only means "this permanent", it doesn't matter that it isn't actually named Thawing Glaciers.


  706.11. If an effect refers to a permanent by name, the effect still tracks that permanent even if it changes names or becomes a copy of something else.


and


  201.4. Text that refers to the object it's on by name means just that particular object and not any other objects with that name, regardless of any name changes caused by game effects.