You can insert as many question modules as you wish in the questionnaire by clicking on the "+" button in front of the module names in the list of modules.
It is possible that the selected module is not the language version corresponding to the language version(s) of the questionnaire. In this case, you will have to create this language version after having selected the modules.
A module can be used in as many questionnaires as desired. Once used in a questionnaire, the structure of a question module can no longer be modified.