Hi,
on the product pages we have some text content that comes from a custom field withe the slug "descripcion-grafico-de-ciclo".
We couldn't find it anymore when trying to translate its content with WPML, and we finally found it in the post field control page, with a pink background color.
I am not sure what happened with it...
How can we add it back to the product pages so that we can edit and translate its content?
From the screenshot it looks like the custom field is no longer part of a Custom Field Group, it has essentially been orphaned.
The simplest explanation is that someone edited the Custom Field Group it belonged to (at Toolset > Custom Fields) and accidentally deleted it. There may be other explanations, but I can't say what happened.
If you use the "Change assignment" link from your screenshot, can you add this custom field back to a Custom Field Group which is assigned to products, then it should appear when editing products.