You can try this to downgrade your project, but please note:
If you used any features from r114 that did not exist in r108, it will break your project.
1) Back up your project.
2) Open your .caproj file with a text editor and edit the line that says something like <saved-with-version>etc.. from 11400 to 10800.
3) Save the file.
This could also be an error with CocoonJS, and if it is, there's nothing Scirra can do to fix it, so you need to take it up with ludei. Good luck!