TinyMCE plugin for plone 5.1

Has anybody get a custom TinyMCE-Plugin working on Plone 5.1.2.1 or <5.2?

I tried sc.embedder and starzel.snippets, but both failed loading with Plone 5.1.x
On Plone 5.2.2 sc.embedder is loading and works

Javascript-Error:
Uncaught TypeError: e.getDoc() is undefined

Linked Topics:

Plone Foundation Code of Conduct