Por fin han respondido al email. Adjunto el mensaje recibido por si interesa a alguien más.

Hi Toni,

No, this is not possible. If you need to collect any other values you could add a field to the product via CATALooK.netStore -> Products -> search for the product -> full page edit -> attributes -> Text Options -> Data Entry Forms -> Select any control type -> add -> assign.

Kind Regards,

Susanne Koehler