You can become a certified interpreter if you (1) earn a Bachelor's Degree in the specific language you plan on working with, (2) complete a certificate program, and (3) pass a valid, reliable certification exam. You could teach a language, although I don't believe there are classes to teach interpretation in general since it is based on fluency of a specific language. Completing the certificate program alone does not necessarily make you "certified" by the court's standards. However, the process of becoming a court interpreter varies by state so you will need to do further research on the process.
I found this information here:
Here is a different list with approved interpretation schools by country: https://www.atanet.org/certification/eligibility_approved.php#us
Additional resource you may find helpful:
Although I provided these links to potential resources, I strongly recommend you look for more reliable sources. You could search programs at universities and the description may include steps for specific career pathways or you could even contact interpreters to ask them about their work.
Since you are already going to school for respiratory therapy, achieving this may be difficult but not at all impossible.
I hope this helps and good luck becoming a certified interpreter!