Libras is the mother language of people who are Deaf or Hard of Hearing (D/HH) in Brazil, characterizing them as people who use visual cues and signs to communicate with the world. Specialized researchers and educators affirm that people who are D/HH first have to be literate in their mother language (L1, sign language) in order to learn the second language (L2, written language). The teaching-learning process of written language as L2 is still a challenge, subject of many investigations and experimentations. This paper presents results and discussions from exploring and understanding problems and solutions of the design for Deaf persons who are sign language (SL) users to adopt an Assistive Technology (AT) product. This AT product refers to a solution for use in the teaching-learning process of Brazilian Portuguese written language as L2. Our methodological approach is to follow the phases of a framework in proposition, which combines concepts of Co-design, adoption of AT, HumanComputer Interaction lifecycle, Semantic Numbers theory and Writing Process. The framework proposed aims to include codesigners in every phase to guarantee higher chances of being accessible and potentially adopted by the stakeholders. Our results were obtained from two semio-participatory workshops, in which we worked with the Stakeholders Diagram and the Evaluation Frame as co-design artifacts. In the former case, many problems, questions, solutions and ideas were presented by stakeholders, to whom cultural diversity and multimodality were central aspects to be considered in the design of an AT product for Deaf people who are SL users.