The Motion 4 application, along with FCP7 and any others, has not disappeared. It’s been moved to a new folder named Final Cut Studio in your Applications folder.
Your templates are in the same place they have always been – root/Library/Application Support/Final Cut Studio/Motion/Templates.
It’s just that Motion 5 does not reference that location, as it stores all it’s projects in User/Movies/Motion Templates/Compositions.
But you can’t copy them there since they won’t be recognized.
I would, from M5, choose File>Open and navigate to the template you want. I’ve tested this workflow and it works for me.
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Mark Spencer
Freelance Producer/Editor/Motion Graphics Artist
Apple-certified Master Trainer
Author, Motion 4 from Peachpit Press
https://www.applemotion.net