In this paper we present the evaluation of an application for the collaborative composition of comics using a pre-defined set of images and sentences. This study is an intermediate step to guide the design of a tablet application for supporting collaborative storytelling between two authors from different cultures and speaking different languages. For this purpose, we assessed the effectiveness of a constrained-text approach for comic composition in which sentences are selected from a library rather than written by the authors. Our results show that the constrained-text approach provides a satisfying form of co-narration, stimulating the authors to stay on topic, while using the available narrative material. The findings of this study have implications for the future design of collaborative storytelling applications for multilingual and cross-cultural scenarios.