Not possible to save a translation when field is not translatable and untranslatable fields are hidden

Since this issue was written, H5P has gotten better i18n support and I _think_ this no longer happens. That said, I'm not certain I understand the steps taken to generate the issue. Here's what I tried:

• Create a content type with an H5P field that uses the H5P Editor as the form widget
• Enable the Content Translation module
• Add an addition language (French) in Admin > Config > Region and Language > Languages
• On Admin > Configuration > Region and Language > Content language and translation, check the "Content" option
• On the same page, check the content type with the H5P field
• Check the "Hide non translatable fields..." option
• Save my changes by clicking "Save configuration"
• Now, edit a node of the content type for which you just added translation
• Click the Translate tab to add (in my case) French translation
• When this form loads, I see the H5P editor and am able to add translated values to H5P fields like Title, Heading, Alt text, etc.
• Save the translation and everything works OK for me

If the original issue poster is still invoved, I'd appreciate some feedback on whether this is a valid test case. If not, I suggest we close this as obsolete.

Thanks for looking into it, @illeace. Closing for now. @berdir - feel free to re-open if this is still an issue you are struggling with.