Improve a few UI items and their corresponding documentation

[brandelune]

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↑ maybe we can remove this part from the template now ?

What does this PR change?

• The PR improves some UI items that were not finalized for the 6.0 release
• It rewords a number of new items

Other information

We need to have a style for error messages, with indication of a subject, a verb, etc. so that have a better understanding of what is going on.