I'm working on a legacy webapp that's mainly focused on reporting large amounts of data - ie tables with 20+ columns reporting financial data. The main problem is table layout inconsistency depending on user interaction and data itself. For example, the width of a particular column changes depending on how big the number/word in the cell is or whether the user has decided to sort that column - an ascending or descending arrow in the header messes up the entire column width. User ends up with a "jumpy" table where the navigation is in a different place with each action.
On top of that, it's an international app meaning the translation also messes up the column title width in different languages.
We're requiring a very small minimum resolution, yet most of our tables are about 1200-1400px wide to fit everything.
Are there any guidelines on how to design a business webapp efficiently and more importantly in a way that the usability doesn't suffer?