Is there a way to get the spell checking language for a certain selection / paragraph?

[Cotspheer]

I have a Word Add-In (TaskPaneApp) using office-js and I want to get the spell checkers language for a certain paragraph. In a document I can specify different languages for a different paragraphs. One can be in de-DE another one in en-US. What I need is the language from the current selection. Is that possible and if so how?

I'm not sure where to look for, everything I find seems to be for VBA like languageId / languageName.

I already know that there is Office.context.contentLanguage but this only returns the language set in the settings which can be different from the current selection / paragraph. One could write something in fr-FR but still have the contentLanguage set to de-DE.