Make UI/UX design recommendations based on industry best practices

We are looking for a UI/UX expert to provide us with design recommendations based on industry best practices. This would be something we would need "on-demand" with some frequency (roughly once a week or once every two weeks). Normally we will already have a functional prototype, but we will need guidance regarding any UI improvements that are recommended. Potential changes could involve a different "flow" of pages, different page layouts, style changes, elements, etc. What we are looking for: - Somebody with experience and knowledge in the field of UI/UX - Recommendations based on standards/heuristics, best practices, etc. (at a conceptual level) - Mendix knowledge would be a huge plus - Must understand Spanish (our pages are in Spanish) What we are not looking for (not yet): - An in-depth analysis of our UI/UX, including user journeys, etc. We can do a light informal version of this for the particular feature being analyzed. - To make changes that are particularly difficult to implement using Mendix Optional: - If you have Mendix skills, we might be able to use you as a front end developer directly. This is entirely optional but desirable.