Large formulas become very confusing. It would be nice if there is a formula editor that inserts, coloring and evaluates the formulas like Visual Studio and that can also be provided with comments and other hints. These formulas must then be displayed in the editor in exactly the same way.
Gareth Hayter commented
Does the Formula Explorer in the FormulaDesk add-in come close to what you want, or are there other features? https://www.formuladesk.com
Denis Kostin commented
We need a more advanced ability to edit and debug formulas. Such a mechanism is described in https://excel.uservoice.com/forums/304921-excel-for-windows-desktop-application/suggestions/31326916-advanced-formula-manager