Thank you for your post.
I am unable to replicate the issue using FileMaker Pro Advanced 15.0.2 under macOS X Sierra 10.12.1, Mac OS X 10.11.6, and Mac OS X 10.10.5. That is, I am able to shift-click and command-click scripts in the Scripts Workspace and print.
What exactly occurs? Specifically, are you able to select the scripts? If so, does the Print dialog box not appear?
Do you have any plug-ins installed/enabled? If so, temporarily disable and try again.
Have you tried quitting and relaunching FIleMaker Pro?