There are two options for that. Option (a) use a random generator and assign the text for each condition (vignette) in a filter. Option (b) use the "databank for content", store the texts as columns (probably what you currently have in your sheet) and use some string in the first column (e.g., A001, A002, ...) as key, which you draw in the random generator. Details in a new question, if required :)