Product and version
FileMaker Pro 15.0.1
OS and version
OS X 10.10.5
iMac Retina 5K 27'' Late 2014
When Pasting (or Importing) a script, a step GTRR with external layout is red marked as an error, even if nothing came broken.
How to replicate
In a multiple file solution, create a script with a gtrr instruction that go to an external layout.
Copy and paste this script (even in the same file).
Then, see how the Gtrr step is red marked as an error, even if nothing came broken.
Just close the Script Workspace and reopen it -- all is fine.