These tabs are usually added through JavaScript, so it's probably just a matter of asking enwikinews what JS they use and reusing that. If eswikinews doesn't have an Opinions namespace yet, you can request it here at Bugzilla.

I can help you copy over the hacky js we use at enwikinews. I'm mostly familiar with the relevant js.

(In reply to comment #1)

These tabs are usually added through JavaScript, so it's probably just a matter
of asking enwikinews what JS they use and reusing that. If eswikinews doesn't
have an Opinions namespace yet, you can request it here at Bugzilla.

We already have that namespace, it is called “Comentarios”.

(In reply to comment #2)

I can help you copy over the hacky js we use at enwikinews. I'm mostly familiar
with the relevant js.

Thank you, I think Jurock dropped a message in your talk page ;)

Yep, I responded. Looks like everything is sorted out.

Resolving as fixed (I suppose it could perhaps be resolved invalid, since this technically is not a mediawiki issue, but meh)