Unfortunately,

Punjabi also is in second tier while Nepali is in the third tier (Hindi is in the first tier like Arabic, so whoever applied first and passed the test they were enlisted right away). Even if you chose punjabi and pass your language, educational, physical etc; you will still be placed in the pool of many others and from among the best will be chosen regardless of the language they can speak or write. Although, if you say you know more other languages than Punjabi your chances of getting selected is comparatively high.

Keep trying, you will succeed. If not this year you can try next year for the Airforce or may be the Navy.