> We just wanted to clarify whether it would still be possible to carry this out under one S2Survey license.
It is. I thought I already had answered that above, but it seems my wording was unclear, sorry.
> Since the questionnaires also differ slightly
Using the getLanguage() function allows for filters, and the tilde (~) allows to omit items in one version or the other. And then, you can also create multiple questionnaires within one survey project. I surely don't want to talk you into a single-project solution. However, from my experience, managing separate surveys goes along with additional efforts.