In the last update of RSG online I have change the Histograms tab for the Distributions tab where a submenu will let you see histograms and bar graphs or boxplots. In the boxplots tab you can find, indeed, boxplots! They show the SE postop by age category, each of the two custom factors and the combination of the two custom factors, which you can switch with a checkbox. With this graphics you can compare results easier.
Also on the Upload data tab, under the data table you can find two tables showing the amount of missing values for the variables that are allowed to have them and the number of unique values for the two custom factors columns. This might give you a better insight of the data you are uploading.