I replaced the URL in the newspublisher class file with this one:
//cdnjs.cloudflare.com/ajax/libs/tinymce/4.9.11/tinymce.min.js work time
though you should be able to do it with the &tinysource property in the NP snippet tag.
I haven’t tested if fully, but it seems to work, and I was able to use the image browser to insert an image. If it doesn’t work with RFM, you may have to switch to elFinder.
Let me know what happens.
It works. Thank you