Cedrela contained in finished musical instruments (e.g. some classical guitars) is exempt from certificate requirements.
If your instrument is exclusively made of species that are either exempt from certificate requirements or not protected by CITES, you can travel safely without this document. Be cautious though, as the presence of one single protected species may require a certificate (MIC or TEC). If your instrument contains a species exempt from certificate requirements, always check whether it also contains species requiring a certificate.