There should be the ability within the Response Viewer to dynamically search responses based on custom variable values, rather than having to go to 'Create Data Filters', creating a criteria and searching in the Response Viewer for that data set.
Multi language questionnaires cannot be populated with custom variables. Please allow that.
It would be great to pre-populate spreadsheet questions with custom variable data. Currently, custom variables can be used only on text box style questions, not with matrices.
Should there be an indicator available which tells your how many and which all custom variables have already been used, so as to save the trouble of going into email list and the survey to check it, and to avoid any possible confusion?