Does language play a role of equal importance in different areas of knowledge?

Yes it does.
Language plays a role of equal importance in each area of knowledge because it is the only worldwide accepted form of communication.
To learn something, to have the knowledge, people have to communicate between each other. Communication allows people to share their knowledge with other people in any area of knowing.
Language is a communication tool. It can be written or spoken and it is important to realize that it is not only that but it can be divided even more in the form of signs and gestures, such as sign and body language.
To spread knowledge language is necessary. Academic searches and projects, music, movies and books, they are frequently translated into common international languages, to be passed on to the international community and even more, to keep it to future generations.
Therefore, language plays a huge role in all areas of knowledge. Just to have a bit of knowledge you need it. It is the foundation for knowledge.