Thanks for this new question, very interesting!
When something is "fuori questione" it means that it is indeed out of the question/off the table.
Depending on the context, the phrase "non se ne parla" can have the same meaning. For instance:
- "Mamma, voglio andare fuori a giocare".
- "Non se ne parla, rimani qui a studiare".
- "Mom, I want to go outdoor to play."
- "It is out of the question, you stay here to study".
As you can see, in the example above the phrase "non se ne parla" can be replaced by "fuori questione" as they both mean "it is out of the question". In a more literal sense, the phrase "non se ne parla" means "we are not going to discuss about this".
However, if we take the sentence below:
"Ci sono molti furti di auto a Pisa, eppure non se ne parla."
"There are many car thefts in Pisa, yet we don't talk about them."
You can see that "non se ne parla" takes a totally different meaning, a literal one, as in "no one talks about it".
To recap, "è fuori questione" and "non se ne parla" both translate as "it is out of the question" depending on the context.
Hope this helps! :)