The so-called "auxiliary" does not mean dispensable. A Chinese painting is an unfinished work without calligraphy inscriptions or annotations. If you have calligraphy, you can't use it in poor calligraphy, otherwise it will not add color to the painting, but will become a failure. So calligraphy is an indispensable part of Chinese painting.
But practicing calligraphy is also a selective practice. You have to choose a calligraphy font that is the same or similar to your Chinese painting style.
Similarly, learning calligraphy should be supplemented by seal cutting. Chinese painting or calligraphy works without seals are also incomplete.