The people this feature is going to target are like
the new user in this thread.
The step back into the Family Tree Manager is going to be an ongoing hitch in the process.
Once you select to create the placeholder tree or select a file to Import, Gramps ought to just create the tree with default name, populate it with data & load the new tree.
It should never come back to the Family Tree Manger … or automatically select the load button if Gramps HAS to return to that dialog in order to dismiss it as the parent dialog.
The renaming of the Tree is an unimportant & distracting step at this stage. The tree can be renamed later when the user is more accustomed to Gramps.